diff --git a/CURRENT_WORKS.md b/CURRENT_WORKS.md
index 7098958..ed846fa 100644
--- a/CURRENT_WORKS.md
+++ b/CURRENT_WORKS.md
@@ -1,3 +1,162 @@
+## 2025-11-20 (수) - ItemMaster Phase 1 API 구현 (핵심 기능)
+
+### 주요 작업
+- Phase 1 핵심 기능 13개 API 엔드포인트 구현
+- Controller, Service, FormRequest 계층 구조 완성
+- SAM API Development Rules 준수 (Service-First, ApiResponse, i18n)
+
+### 추가된 파일
+
+#### Controllers (4개)
+1. **app/Http/Controllers/Api/V1/ItemMaster/ItemMasterController.php**
+   - init() - 전체 초기 데이터 로드
+
+2. **app/Http/Controllers/Api/V1/ItemMaster/ItemPageController.php**
+   - index(), store(), update(), destroy()
+   - 페이지 관리 (섹션/필드 중첩 포함)
+
+3. **app/Http/Controllers/Api/V1/ItemMaster/ItemSectionController.php**
+   - store(), update(), destroy(), reorder()
+   - 섹션 관리 및 순서 변경
+
+4. **app/Http/Controllers/Api/V1/ItemMaster/ItemFieldController.php**
+   - store(), update(), destroy(), reorder()
+   - 필드 관리 및 순서 변경
+
+#### Services (4개)
+1. **app/Services/ItemMaster/ItemMasterService.php**
+   - init() - pages, sectionTemplates, masterFields, customTabs, unitOptions 로드
+   - Eager Loading으로 N+1 쿼리 방지
+
+2. **app/Services/ItemMaster/ItemPageService.php**
+   - CRUD + Cascade Soft Delete
+   - Multi-tenant 스코프 자동 적용
+
+3. **app/Services/ItemMaster/ItemSectionService.php**
+   - CRUD + reorder (order_no 자동 계산)
+   - Cascade Soft Delete (하위 필드/BOM 항목 포함)
+
+4. **app/Services/ItemMaster/ItemFieldService.php**
+   - CRUD + reorder
+   - JSON 필드 지원 (display_condition, validation_rules, options, properties)
+
+#### FormRequests (7개)
+1. **app/Http/Requests/ItemMaster/ItemPageStoreRequest.php**
+   - page_name (required, max:255)
+   - item_type (required, in:FG,PT,SM,RM,CS)
+   - absolute_path (nullable, max:500)
+
+2. **app/Http/Requests/ItemMaster/ItemPageUpdateRequest.php**
+   - page_name (sometimes)
+   - absolute_path (nullable)
+
+3. **app/Http/Requests/ItemMaster/ItemSectionStoreRequest.php**
+   - title (required, max:255)
+   - type (required, in:fields,bom)
+
+4. **app/Http/Requests/ItemMaster/ItemSectionUpdateRequest.php**
+   - title (sometimes)
+
+5. **app/Http/Requests/ItemMaster/ItemFieldStoreRequest.php**
+   - field_name (required), field_type (required, enum)
+   - is_required, placeholder, options, properties (nullable)
+   - display_condition, validation_rules (array)
+
+6. **app/Http/Requests/ItemMaster/ItemFieldUpdateRequest.php**
+   - 모든 필드 sometimes
+
+7. **app/Http/Requests/ItemMaster/ReorderRequest.php**
+   - items (required, array)
+   - items.*.id, items.*.order_no (required)
+
+### 수정된 파일
+
+1. **routes/api.php**
+   - ItemMaster 관련 use 문 4개 추가
+   - `/v1/item-master/*` 라우트 그룹 추가
+   - 13개 엔드포인트 등록:
+     - GET /init
+     - GET/POST/PUT/DELETE /pages
+     - POST/PUT/DELETE /pages/{pageId}/sections
+     - PUT /pages/{pageId}/sections/reorder
+     - POST/PUT/DELETE /sections/{sectionId}/fields
+     - PUT /sections/{sectionId}/fields/reorder
+
+### 작업 내용
+
+#### API 엔드포인트 (13개)
+1. ✅ GET `/init` - 전체 초기 데이터
+2. ✅ GET `/pages` - 페이지 목록 (item_type 필터)
+3. ✅ POST `/pages` - 페이지 생성
+4. ✅ PUT `/pages/{id}` - 페이지 수정
+5. ✅ DELETE `/pages/{id}` - 페이지 삭제 (Cascade)
+6. ✅ POST `/pages/{pageId}/sections` - 섹션 생성
+7. ✅ PUT `/sections/{id}` - 섹션 수정
+8. ✅ DELETE `/sections/{id}` - 섹션 삭제 (Cascade)
+9. ✅ PUT `/pages/{pageId}/sections/reorder` - 섹션 순서 변경
+10. ✅ POST `/sections/{sectionId}/fields` - 필드 생성
+11. ✅ PUT `/fields/{id}` - 필드 수정
+12. ✅ DELETE `/fields/{id}` - 필드 삭제
+13. ✅ PUT `/sections/{sectionId}/fields/reorder` - 필드 순서 변경
+
+#### 기술적 특징
+
+**Service-First 패턴**:
+- Controller는 DI + ApiResponse::handle()만 사용
+- 모든 비즈니스 로직은 Service에 구현
+- Service extends Service (tenantId(), apiUserId() 활용)
+
+**Multi-tenant 지원**:
+- 모든 Service 메서드에서 tenantId() 검증
+- BelongsToTenant 스코프 자동 적용
+- Cascade Soft Delete시 tenant_id 검증
+
+**실시간 저장**:
+- 모든 CUD 작업 즉시 처리
+- order_no 자동 계산 (마지막 + 1)
+- reorder는 배열로 한 번에 처리
+
+**i18n 메시지**:
+- __('message.fetched'), __('message.created')
+- __('message.updated'), __('message.deleted')
+- __('message.reordered'), __('error.not_found')
+
+### 검증 결과
+
+**라우트 테스트**:
+```bash
+php artisan route:list --path=item-master
+# 결과: 13개 엔드포인트 정상 등록
+```
+
+**Pint 검사**:
+```bash
+./vendor/bin/pint --test app/Http/Controllers/Api/V1/ItemMaster/ app/Services/ItemMaster/ app/Http/Requests/ItemMaster/
+# 결과: 15 files PASS
+```
+
+### 다음 단계 (Phase 2-3)
+
+**Phase 2 (확장 기능)** - 예정:
+- BOM 항목 관리 (3개 엔드포인트)
+- 섹션 템플릿 (4개 엔드포인트)
+- 마스터 필드 (4개 엔드포인트)
+
+**Phase 3 (부가 기능)** - 예정:
+- 커스텀 탭 (5개 엔드포인트)
+- 단위 옵션 (3개 엔드포인트)
+
+**Swagger 문서** - 필요:
+- app/Swagger/v1/ItemMasterApi.php 작성
+- 13개 엔드포인트 스키마 정의
+
+### Git 커밋
+```bash
+# 커밋 예정
+```
+
+---
+
 ## 2025-11-20 (수) - ItemMaster 데이터베이스 구조 구축
 
 ### 주요 작업
diff --git a/app/Http/Controllers/Api/V1/ItemMaster/ItemFieldController.php b/app/Http/Controllers/Api/V1/ItemMaster/ItemFieldController.php
new file mode 100644
index 0000000..446a9f4
--- /dev/null
+++ b/app/Http/Controllers/Api/V1/ItemMaster/ItemFieldController.php
@@ -0,0 +1,67 @@
+<?php
+
+namespace App\Http\Controllers\Api\V1\ItemMaster;
+
+use App\Helpers\ApiResponse;
+use App\Http\Controllers\Controller;
+use App\Http\Requests\ItemMaster\ItemFieldStoreRequest;
+use App\Http\Requests\ItemMaster\ItemFieldUpdateRequest;
+use App\Http\Requests\ItemMaster\ReorderRequest;
+use App\Services\ItemMaster\ItemFieldService;
+
+class ItemFieldController extends Controller
+{
+    public function __construct(private ItemFieldService $service) {}
+
+    /**
+     * 필드 생성
+     *
+     * POST /api/v1/item-master/sections/{sectionId}/fields
+     */
+    public function store(int $sectionId, ItemFieldStoreRequest $request)
+    {
+        return ApiResponse::handle(function () use ($sectionId, $request) {
+            return $this->service->store($sectionId, $request->validated());
+        }, __('message.created'));
+    }
+
+    /**
+     * 필드 수정
+     *
+     * PUT /api/v1/item-master/fields/{id}
+     */
+    public function update(int $id, ItemFieldUpdateRequest $request)
+    {
+        return ApiResponse::handle(function () use ($id, $request) {
+            return $this->service->update($id, $request->validated());
+        }, __('message.updated'));
+    }
+
+    /**
+     * 필드 삭제 (Soft Delete)
+     *
+     * DELETE /api/v1/item-master/fields/{id}
+     */
+    public function destroy(int $id)
+    {
+        return ApiResponse::handle(function () use ($id) {
+            $this->service->destroy($id);
+
+            return 'success';
+        }, __('message.deleted'));
+    }
+
+    /**
+     * 필드 순서 변경
+     *
+     * PUT /api/v1/item-master/sections/{sectionId}/fields/reorder
+     */
+    public function reorder(int $sectionId, ReorderRequest $request)
+    {
+        return ApiResponse::handle(function () use ($sectionId, $request) {
+            $this->service->reorder($sectionId, $request->validated()['items']);
+
+            return 'success';
+        }, __('message.reordered'));
+    }
+}
diff --git a/app/Http/Controllers/Api/V1/ItemMaster/ItemMasterController.php b/app/Http/Controllers/Api/V1/ItemMaster/ItemMasterController.php
new file mode 100644
index 0000000..99caf8d
--- /dev/null
+++ b/app/Http/Controllers/Api/V1/ItemMaster/ItemMasterController.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace App\Http\Controllers\Api\V1\ItemMaster;
+
+use App\Helpers\ApiResponse;
+use App\Http\Controllers\Controller;
+use App\Services\ItemMaster\ItemMasterService;
+
+class ItemMasterController extends Controller
+{
+    public function __construct(private ItemMasterService $service) {}
+
+    /**
+     * 초기화 API - 전체 데이터 로드
+     *
+     * GET /api/v1/item-master/init
+     */
+    public function init()
+    {
+        return ApiResponse::handle(function () {
+            return $this->service->init();
+        }, __('message.fetched'));
+    }
+}
diff --git a/app/Http/Controllers/Api/V1/ItemMaster/ItemPageController.php b/app/Http/Controllers/Api/V1/ItemMaster/ItemPageController.php
new file mode 100644
index 0000000..26812b2
--- /dev/null
+++ b/app/Http/Controllers/Api/V1/ItemMaster/ItemPageController.php
@@ -0,0 +1,67 @@
+<?php
+
+namespace App\Http\Controllers\Api\V1\ItemMaster;
+
+use App\Helpers\ApiResponse;
+use App\Http\Controllers\Controller;
+use App\Http\Requests\ItemMaster\ItemPageStoreRequest;
+use App\Http\Requests\ItemMaster\ItemPageUpdateRequest;
+use App\Services\ItemMaster\ItemPageService;
+use Illuminate\Http\Request;
+
+class ItemPageController extends Controller
+{
+    public function __construct(private ItemPageService $service) {}
+
+    /**
+     * 페이지 목록 조회 (섹션/필드 중첩 포함)
+     *
+     * GET /api/v1/item-master/pages?item_type=FG
+     */
+    public function index(Request $request)
+    {
+        return ApiResponse::handle(function () use ($request) {
+            $itemType = $request->input('item_type');
+
+            return $this->service->index($itemType);
+        }, __('message.fetched'));
+    }
+
+    /**
+     * 페이지 생성
+     *
+     * POST /api/v1/item-master/pages
+     */
+    public function store(ItemPageStoreRequest $request)
+    {
+        return ApiResponse::handle(function () use ($request) {
+            return $this->service->store($request->validated());
+        }, __('message.created'));
+    }
+
+    /**
+     * 페이지 수정
+     *
+     * PUT /api/v1/item-master/pages/{id}
+     */
+    public function update(int $id, ItemPageUpdateRequest $request)
+    {
+        return ApiResponse::handle(function () use ($id, $request) {
+            return $this->service->update($id, $request->validated());
+        }, __('message.updated'));
+    }
+
+    /**
+     * 페이지 삭제 (Soft Delete)
+     *
+     * DELETE /api/v1/item-master/pages/{id}
+     */
+    public function destroy(int $id)
+    {
+        return ApiResponse::handle(function () use ($id) {
+            $this->service->destroy($id);
+
+            return 'success';
+        }, __('message.deleted'));
+    }
+}
diff --git a/app/Http/Controllers/Api/V1/ItemMaster/ItemSectionController.php b/app/Http/Controllers/Api/V1/ItemMaster/ItemSectionController.php
new file mode 100644
index 0000000..96717f1
--- /dev/null
+++ b/app/Http/Controllers/Api/V1/ItemMaster/ItemSectionController.php
@@ -0,0 +1,67 @@
+<?php
+
+namespace App\Http\Controllers\Api\V1\ItemMaster;
+
+use App\Helpers\ApiResponse;
+use App\Http\Controllers\Controller;
+use App\Http\Requests\ItemMaster\ItemSectionStoreRequest;
+use App\Http\Requests\ItemMaster\ItemSectionUpdateRequest;
+use App\Http\Requests\ItemMaster\ReorderRequest;
+use App\Services\ItemMaster\ItemSectionService;
+
+class ItemSectionController extends Controller
+{
+    public function __construct(private ItemSectionService $service) {}
+
+    /**
+     * 섹션 생성
+     *
+     * POST /api/v1/item-master/pages/{pageId}/sections
+     */
+    public function store(int $pageId, ItemSectionStoreRequest $request)
+    {
+        return ApiResponse::handle(function () use ($pageId, $request) {
+            return $this->service->store($pageId, $request->validated());
+        }, __('message.created'));
+    }
+
+    /**
+     * 섹션 수정
+     *
+     * PUT /api/v1/item-master/sections/{id}
+     */
+    public function update(int $id, ItemSectionUpdateRequest $request)
+    {
+        return ApiResponse::handle(function () use ($id, $request) {
+            return $this->service->update($id, $request->validated());
+        }, __('message.updated'));
+    }
+
+    /**
+     * 섹션 삭제 (Soft Delete)
+     *
+     * DELETE /api/v1/item-master/sections/{id}
+     */
+    public function destroy(int $id)
+    {
+        return ApiResponse::handle(function () use ($id) {
+            $this->service->destroy($id);
+
+            return 'success';
+        }, __('message.deleted'));
+    }
+
+    /**
+     * 섹션 순서 변경
+     *
+     * PUT /api/v1/item-master/pages/{pageId}/sections/reorder
+     */
+    public function reorder(int $pageId, ReorderRequest $request)
+    {
+        return ApiResponse::handle(function () use ($pageId, $request) {
+            $this->service->reorder($pageId, $request->validated()['items']);
+
+            return 'success';
+        }, __('message.reordered'));
+    }
+}
diff --git a/app/Http/Requests/ItemMaster/ItemFieldStoreRequest.php b/app/Http/Requests/ItemMaster/ItemFieldStoreRequest.php
new file mode 100644
index 0000000..e46f436
--- /dev/null
+++ b/app/Http/Requests/ItemMaster/ItemFieldStoreRequest.php
@@ -0,0 +1,28 @@
+<?php
+
+namespace App\Http\Requests\ItemMaster;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class ItemFieldStoreRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'field_name' => 'required|string|max:255',
+            'field_type' => 'required|in:textbox,number,dropdown,checkbox,date,textarea',
+            'is_required' => 'nullable|boolean',
+            'default_value' => 'nullable|string',
+            'placeholder' => 'nullable|string|max:255',
+            'display_condition' => 'nullable|array',
+            'validation_rules' => 'nullable|array',
+            'options' => 'nullable|array',
+            'properties' => 'nullable|array',
+        ];
+    }
+}
diff --git a/app/Http/Requests/ItemMaster/ItemFieldUpdateRequest.php b/app/Http/Requests/ItemMaster/ItemFieldUpdateRequest.php
new file mode 100644
index 0000000..6ac3590
--- /dev/null
+++ b/app/Http/Requests/ItemMaster/ItemFieldUpdateRequest.php
@@ -0,0 +1,28 @@
+<?php
+
+namespace App\Http\Requests\ItemMaster;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class ItemFieldUpdateRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'field_name' => 'sometimes|string|max:255',
+            'field_type' => 'sometimes|in:textbox,number,dropdown,checkbox,date,textarea',
+            'is_required' => 'nullable|boolean',
+            'default_value' => 'nullable|string',
+            'placeholder' => 'nullable|string|max:255',
+            'display_condition' => 'nullable|array',
+            'validation_rules' => 'nullable|array',
+            'options' => 'nullable|array',
+            'properties' => 'nullable|array',
+        ];
+    }
+}
diff --git a/app/Http/Requests/ItemMaster/ItemPageStoreRequest.php b/app/Http/Requests/ItemMaster/ItemPageStoreRequest.php
new file mode 100644
index 0000000..38f8c56
--- /dev/null
+++ b/app/Http/Requests/ItemMaster/ItemPageStoreRequest.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace App\Http\Requests\ItemMaster;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class ItemPageStoreRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'page_name' => 'required|string|max:255',
+            'item_type' => 'required|in:FG,PT,SM,RM,CS',
+            'absolute_path' => 'nullable|string|max:500',
+        ];
+    }
+}
diff --git a/app/Http/Requests/ItemMaster/ItemPageUpdateRequest.php b/app/Http/Requests/ItemMaster/ItemPageUpdateRequest.php
new file mode 100644
index 0000000..9253f5c
--- /dev/null
+++ b/app/Http/Requests/ItemMaster/ItemPageUpdateRequest.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace App\Http\Requests\ItemMaster;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class ItemPageUpdateRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'page_name' => 'sometimes|string|max:255',
+            'absolute_path' => 'nullable|string|max:500',
+        ];
+    }
+}
diff --git a/app/Http/Requests/ItemMaster/ItemSectionStoreRequest.php b/app/Http/Requests/ItemMaster/ItemSectionStoreRequest.php
new file mode 100644
index 0000000..968aa08
--- /dev/null
+++ b/app/Http/Requests/ItemMaster/ItemSectionStoreRequest.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace App\Http\Requests\ItemMaster;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class ItemSectionStoreRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'title' => 'required|string|max:255',
+            'type' => 'required|in:fields,bom',
+        ];
+    }
+}
diff --git a/app/Http/Requests/ItemMaster/ItemSectionUpdateRequest.php b/app/Http/Requests/ItemMaster/ItemSectionUpdateRequest.php
new file mode 100644
index 0000000..40c3dd0
--- /dev/null
+++ b/app/Http/Requests/ItemMaster/ItemSectionUpdateRequest.php
@@ -0,0 +1,20 @@
+<?php
+
+namespace App\Http\Requests\ItemMaster;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class ItemSectionUpdateRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'title' => 'sometimes|string|max:255',
+        ];
+    }
+}
diff --git a/app/Http/Requests/ItemMaster/ReorderRequest.php b/app/Http/Requests/ItemMaster/ReorderRequest.php
new file mode 100644
index 0000000..501210a
--- /dev/null
+++ b/app/Http/Requests/ItemMaster/ReorderRequest.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace App\Http\Requests\ItemMaster;
+
+use Illuminate\Foundation\Http\FormRequest;
+
+class ReorderRequest extends FormRequest
+{
+    public function authorize(): bool
+    {
+        return true;
+    }
+
+    public function rules(): array
+    {
+        return [
+            'items' => 'required|array|min:1',
+            'items.*.id' => 'required|integer|exists:item_sections,id',
+            'items.*.order_no' => 'required|integer|min:0',
+        ];
+    }
+}
diff --git a/app/Services/ItemMaster/ItemFieldService.php b/app/Services/ItemMaster/ItemFieldService.php
new file mode 100644
index 0000000..6d18397
--- /dev/null
+++ b/app/Services/ItemMaster/ItemFieldService.php
@@ -0,0 +1,115 @@
+<?php
+
+namespace App\Services\ItemMaster;
+
+use App\Models\ItemMaster\ItemField;
+use App\Services\Service;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+
+class ItemFieldService extends Service
+{
+    /**
+     * 필드 생성
+     */
+    public function store(int $sectionId, array $data): ItemField
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        // order_no 자동 계산 (해당 섹션의 마지막 필드 + 1)
+        $maxOrder = ItemField::where('tenant_id', $tenantId)
+            ->where('section_id', $sectionId)
+            ->max('order_no');
+
+        $field = ItemField::create([
+            'tenant_id' => $tenantId,
+            'section_id' => $sectionId,
+            'field_name' => $data['field_name'],
+            'field_type' => $data['field_type'],
+            'order_no' => ($maxOrder ?? -1) + 1,
+            'is_required' => $data['is_required'] ?? false,
+            'default_value' => $data['default_value'] ?? null,
+            'placeholder' => $data['placeholder'] ?? null,
+            'display_condition' => $data['display_condition'] ?? null,
+            'validation_rules' => $data['validation_rules'] ?? null,
+            'options' => $data['options'] ?? null,
+            'properties' => $data['properties'] ?? null,
+            'created_by' => $userId,
+        ]);
+
+        return $field;
+    }
+
+    /**
+     * 필드 수정
+     */
+    public function update(int $id, array $data): ItemField
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        $field = ItemField::where('tenant_id', $tenantId)
+            ->where('id', $id)
+            ->first();
+
+        if (! $field) {
+            throw new NotFoundHttpException(__('error.not_found'));
+        }
+
+        $field->update([
+            'field_name' => $data['field_name'] ?? $field->field_name,
+            'field_type' => $data['field_type'] ?? $field->field_type,
+            'is_required' => $data['is_required'] ?? $field->is_required,
+            'default_value' => $data['default_value'] ?? $field->default_value,
+            'placeholder' => $data['placeholder'] ?? $field->placeholder,
+            'display_condition' => $data['display_condition'] ?? $field->display_condition,
+            'validation_rules' => $data['validation_rules'] ?? $field->validation_rules,
+            'options' => $data['options'] ?? $field->options,
+            'properties' => $data['properties'] ?? $field->properties,
+            'updated_by' => $userId,
+        ]);
+
+        return $field;
+    }
+
+    /**
+     * 필드 삭제 (Soft Delete)
+     */
+    public function destroy(int $id): void
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        $field = ItemField::where('tenant_id', $tenantId)
+            ->where('id', $id)
+            ->first();
+
+        if (! $field) {
+            throw new NotFoundHttpException(__('error.not_found'));
+        }
+
+        $field->update(['deleted_by' => $userId]);
+        $field->delete();
+    }
+
+    /**
+     * 필드 순서 변경
+     *
+     * @param  array  $items  [['id' => 1, 'order_no' => 0], ['id' => 2, 'order_no' => 1], ...]
+     */
+    public function reorder(int $sectionId, array $items): void
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        foreach ($items as $item) {
+            ItemField::where('tenant_id', $tenantId)
+                ->where('section_id', $sectionId)
+                ->where('id', $item['id'])
+                ->update([
+                    'order_no' => $item['order_no'],
+                    'updated_by' => $userId,
+                ]);
+        }
+    }
+}
diff --git a/app/Services/ItemMaster/ItemMasterService.php b/app/Services/ItemMaster/ItemMasterService.php
new file mode 100644
index 0000000..2a3f24f
--- /dev/null
+++ b/app/Services/ItemMaster/ItemMasterService.php
@@ -0,0 +1,64 @@
+<?php
+
+namespace App\Services\ItemMaster;
+
+use App\Models\ItemMaster\CustomTab;
+use App\Models\ItemMaster\ItemMasterField;
+use App\Models\ItemMaster\ItemPage;
+use App\Models\ItemMaster\SectionTemplate;
+use App\Models\ItemMaster\UnitOption;
+use App\Services\Service;
+
+class ItemMasterService extends Service
+{
+    /**
+     * 초기화 데이터 로드
+     *
+     * - pages (섹션/필드 중첩)
+     * - sectionTemplates
+     * - masterFields
+     * - customTabs (columnSetting 포함)
+     * - unitOptions
+     */
+    public function init(): array
+    {
+        $tenantId = $this->tenantId();
+
+        // 1. 페이지 (섹션 → 필드 중첩)
+        $pages = ItemPage::with([
+            'sections' => function ($query) {
+                $query->orderBy('order_no');
+            },
+            'sections.fields' => function ($query) {
+                $query->orderBy('order_no');
+            },
+            'sections.bomItems',
+        ])
+            ->where('tenant_id', $tenantId)
+            ->where('is_active', 1)
+            ->get();
+
+        // 2. 섹션 템플릿
+        $sectionTemplates = SectionTemplate::where('tenant_id', $tenantId)->get();
+
+        // 3. 마스터 필드
+        $masterFields = ItemMasterField::where('tenant_id', $tenantId)->get();
+
+        // 4. 커스텀 탭 (컬럼 설정 포함)
+        $customTabs = CustomTab::with('columnSetting')
+            ->where('tenant_id', $tenantId)
+            ->orderBy('order_no')
+            ->get();
+
+        // 5. 단위 옵션
+        $unitOptions = UnitOption::where('tenant_id', $tenantId)->get();
+
+        return [
+            'pages' => $pages,
+            'sectionTemplates' => $sectionTemplates,
+            'masterFields' => $masterFields,
+            'customTabs' => $customTabs,
+            'unitOptions' => $unitOptions,
+        ];
+    }
+}
diff --git a/app/Services/ItemMaster/ItemPageService.php b/app/Services/ItemMaster/ItemPageService.php
new file mode 100644
index 0000000..4ab5223
--- /dev/null
+++ b/app/Services/ItemMaster/ItemPageService.php
@@ -0,0 +1,123 @@
+<?php
+
+namespace App\Services\ItemMaster;
+
+use App\Models\ItemMaster\ItemPage;
+use App\Services\Service;
+use Illuminate\Support\Collection;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+
+class ItemPageService extends Service
+{
+    /**
+     * 페이지 목록 조회 (섹션/필드 중첩)
+     */
+    public function index(?string $itemType = null): Collection
+    {
+        $tenantId = $this->tenantId();
+
+        $query = ItemPage::with([
+            'sections' => function ($query) {
+                $query->orderBy('order_no');
+            },
+            'sections.fields' => function ($query) {
+                $query->orderBy('order_no');
+            },
+            'sections.bomItems',
+        ])
+            ->where('tenant_id', $tenantId)
+            ->where('is_active', 1);
+
+        if ($itemType) {
+            $query->where('item_type', strtoupper($itemType));
+        }
+
+        return $query->get();
+    }
+
+    /**
+     * 페이지 생성
+     */
+    public function store(array $data): ItemPage
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        $page = ItemPage::create([
+            'tenant_id' => $tenantId,
+            'page_name' => $data['page_name'],
+            'item_type' => $data['item_type'],
+            'absolute_path' => $data['absolute_path'] ?? null,
+            'is_active' => true,
+            'created_by' => $userId,
+        ]);
+
+        // 관계 로드
+        $page->load(['sections']);
+
+        return $page;
+    }
+
+    /**
+     * 페이지 수정
+     */
+    public function update(int $id, array $data): ItemPage
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        $page = ItemPage::where('tenant_id', $tenantId)
+            ->where('id', $id)
+            ->first();
+
+        if (! $page) {
+            throw new NotFoundHttpException(__('error.not_found'));
+        }
+
+        $page->update([
+            'page_name' => $data['page_name'] ?? $page->page_name,
+            'absolute_path' => $data['absolute_path'] ?? $page->absolute_path,
+            'updated_by' => $userId,
+        ]);
+
+        $page->load(['sections.fields', 'sections.bomItems']);
+
+        return $page;
+    }
+
+    /**
+     * 페이지 삭제 (Soft Delete)
+     */
+    public function destroy(int $id): void
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        $page = ItemPage::where('tenant_id', $tenantId)
+            ->where('id', $id)
+            ->first();
+
+        if (! $page) {
+            throw new NotFoundHttpException(__('error.not_found'));
+        }
+
+        $page->update(['deleted_by' => $userId]);
+        $page->delete();
+
+        // Cascade: 하위 섹션/필드도 Soft Delete
+        foreach ($page->sections as $section) {
+            $section->update(['deleted_by' => $userId]);
+            $section->delete();
+
+            foreach ($section->fields as $field) {
+                $field->update(['deleted_by' => $userId]);
+                $field->delete();
+            }
+
+            foreach ($section->bomItems as $bomItem) {
+                $bomItem->update(['deleted_by' => $userId]);
+                $bomItem->delete();
+            }
+        }
+    }
+}
diff --git a/app/Services/ItemMaster/ItemSectionService.php b/app/Services/ItemMaster/ItemSectionService.php
new file mode 100644
index 0000000..6a66280
--- /dev/null
+++ b/app/Services/ItemMaster/ItemSectionService.php
@@ -0,0 +1,115 @@
+<?php
+
+namespace App\Services\ItemMaster;
+
+use App\Models\ItemMaster\ItemSection;
+use App\Services\Service;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+
+class ItemSectionService extends Service
+{
+    /**
+     * 섹션 생성
+     */
+    public function store(int $pageId, array $data): ItemSection
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        // order_no 자동 계산 (해당 페이지의 마지막 섹션 + 1)
+        $maxOrder = ItemSection::where('tenant_id', $tenantId)
+            ->where('page_id', $pageId)
+            ->max('order_no');
+
+        $section = ItemSection::create([
+            'tenant_id' => $tenantId,
+            'page_id' => $pageId,
+            'title' => $data['title'],
+            'type' => $data['type'],
+            'order_no' => ($maxOrder ?? -1) + 1,
+            'created_by' => $userId,
+        ]);
+
+        $section->load(['fields', 'bomItems']);
+
+        return $section;
+    }
+
+    /**
+     * 섹션 수정
+     */
+    public function update(int $id, array $data): ItemSection
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        $section = ItemSection::where('tenant_id', $tenantId)
+            ->where('id', $id)
+            ->first();
+
+        if (! $section) {
+            throw new NotFoundHttpException(__('error.not_found'));
+        }
+
+        $section->update([
+            'title' => $data['title'] ?? $section->title,
+            'updated_by' => $userId,
+        ]);
+
+        $section->load(['fields', 'bomItems']);
+
+        return $section;
+    }
+
+    /**
+     * 섹션 삭제 (Soft Delete)
+     */
+    public function destroy(int $id): void
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        $section = ItemSection::where('tenant_id', $tenantId)
+            ->where('id', $id)
+            ->first();
+
+        if (! $section) {
+            throw new NotFoundHttpException(__('error.not_found'));
+        }
+
+        $section->update(['deleted_by' => $userId]);
+        $section->delete();
+
+        // Cascade: 하위 필드도 Soft Delete
+        foreach ($section->fields as $field) {
+            $field->update(['deleted_by' => $userId]);
+            $field->delete();
+        }
+
+        foreach ($section->bomItems as $bomItem) {
+            $bomItem->update(['deleted_by' => $userId]);
+            $bomItem->delete();
+        }
+    }
+
+    /**
+     * 섹션 순서 변경
+     *
+     * @param  array  $items  [['id' => 1, 'order_no' => 0], ['id' => 2, 'order_no' => 1], ...]
+     */
+    public function reorder(int $pageId, array $items): void
+    {
+        $tenantId = $this->tenantId();
+        $userId = $this->apiUserId();
+
+        foreach ($items as $item) {
+            ItemSection::where('tenant_id', $tenantId)
+                ->where('page_id', $pageId)
+                ->where('id', $item['id'])
+                ->update([
+                    'order_no' => $item['order_no'],
+                    'updated_by' => $userId,
+                ]);
+        }
+    }
+}
diff --git a/routes/api.php b/routes/api.php
index 70e9066..1281c62 100644
--- a/routes/api.php
+++ b/routes/api.php
@@ -19,6 +19,10 @@
 use App\Http\Controllers\Api\V1\EstimateController;
 use App\Http\Controllers\Api\V1\FileStorageController;
 use App\Http\Controllers\Api\V1\FolderController;
+use App\Http\Controllers\Api\V1\ItemMaster\ItemFieldController;
+use App\Http\Controllers\Api\V1\ItemMaster\ItemMasterController;
+use App\Http\Controllers\Api\V1\ItemMaster\ItemPageController;
+use App\Http\Controllers\Api\V1\ItemMaster\ItemSectionController;
 use App\Http\Controllers\Api\V1\MaterialController;
 use App\Http\Controllers\Api\V1\MenuController;
 use App\Http\Controllers\Api\V1\ModelSetController;
@@ -469,6 +473,30 @@
             Route::post('/reorder', [FolderController::class, 'reorder'])->name('v1.folders.reorder');                           // 폴더 순서 변경
         });
 
+        // 품목기준관리 (ItemMaster) API
+        Route::prefix('item-master')->group(function () {
+            // 초기화
+            Route::get('/init', [ItemMasterController::class, 'init'])->name('v1.item-master.init');
+
+            // 페이지 관리
+            Route::get('/pages', [ItemPageController::class, 'index'])->name('v1.item-master.pages.index');
+            Route::post('/pages', [ItemPageController::class, 'store'])->name('v1.item-master.pages.store');
+            Route::put('/pages/{id}', [ItemPageController::class, 'update'])->name('v1.item-master.pages.update');
+            Route::delete('/pages/{id}', [ItemPageController::class, 'destroy'])->name('v1.item-master.pages.destroy');
+
+            // 섹션 관리
+            Route::post('/pages/{pageId}/sections', [ItemSectionController::class, 'store'])->name('v1.item-master.sections.store');
+            Route::put('/sections/{id}', [ItemSectionController::class, 'update'])->name('v1.item-master.sections.update');
+            Route::delete('/sections/{id}', [ItemSectionController::class, 'destroy'])->name('v1.item-master.sections.destroy');
+            Route::put('/pages/{pageId}/sections/reorder', [ItemSectionController::class, 'reorder'])->name('v1.item-master.sections.reorder');
+
+            // 필드 관리
+            Route::post('/sections/{sectionId}/fields', [ItemFieldController::class, 'store'])->name('v1.item-master.fields.store');
+            Route::put('/fields/{id}', [ItemFieldController::class, 'update'])->name('v1.item-master.fields.update');
+            Route::delete('/fields/{id}', [ItemFieldController::class, 'destroy'])->name('v1.item-master.fields.destroy');
+            Route::put('/sections/{sectionId}/fields/reorder', [ItemFieldController::class, 'reorder'])->name('v1.item-master.fields.reorder');
+        });
+
     });
 
     // 공유 링크 다운로드 (인증 불필요 - auth.apikey 그룹 밖)