diff --git a/app/Http/Controllers/Api/Admin/DocumentTemplateApiController.php b/app/Http/Controllers/Api/Admin/DocumentTemplateApiController.php
index b48c43ad..a05462c2 100644
--- a/app/Http/Controllers/Api/Admin/DocumentTemplateApiController.php
+++ b/app/Http/Controllers/Api/Admin/DocumentTemplateApiController.php
@@ -617,19 +617,18 @@ public function getCommonCodes(string $group): JsonResponse
     }
 
     /**
-     * 관계 데이터 저장
+     * 관계 데이터 저장 (ID 보존 upsert 방식)
+     *
+     * sections/columns는 기존 ID를 보존하여 document_data 참조가 깨지지 않도록 함.
+     * 나머지(approval_lines, basic_fields 등)는 단순 관계라 삭제→재생성.
      */
     private function saveRelations(DocumentTemplate $template, array $data, bool $deleteExisting = false): void
     {
-        // 기존 데이터 삭제 (수정 시)
+        // 단순 관계: 삭제 → 재생성 (document_data가 참조하지 않는 테이블)
         if ($deleteExisting) {
             $template->approvalLines()->delete();
             $template->basicFields()->delete();
-            // sections는 cascade로 items도 함께 삭제됨
-            $template->sections()->delete();
-            $template->columns()->delete();
             $template->sectionFields()->delete();
-            // links는 cascade로 linkValues도 함께 삭제됨
             $template->links()->delete();
         }
 
@@ -661,20 +660,42 @@ private function saveRelations(DocumentTemplate $template, array $data, bool $de
             }
         }
 
-        // 섹션 및 항목
-        if (! empty($data['sections'])) {
+        // 섹션 및 항목: ID 보존 upsert (document_data.section_id 참조 보호)
+        if (isset($data['sections'])) {
+            $incomingIds = collect($data['sections'])->pluck('id')->filter()->toArray();
+            // 요청에 없는 섹션만 삭제 (cascade로 items도 삭제)
+            if ($deleteExisting) {
+                $template->sections()->whereNotIn('id', $incomingIds)->each(function ($section) {
+                    $section->items()->delete();
+                    $section->delete();
+                });
+            }
+
             foreach ($data['sections'] as $sIndex => $section) {
-                $newSection = DocumentTemplateSection::create([
-                    'template_id' => $template->id,
+                $sectionData = [
                     'title' => $section['title'] ?? '',
                     'image_path' => $section['image_path'] ?? null,
                     'sort_order' => $sIndex,
-                ]);
+                ];
+
+                if (! empty($section['id']) && $template->sections()->where('id', $section['id'])->exists()) {
+                    $existing = $template->sections()->where('id', $section['id'])->first();
+                    $existing->update($sectionData);
+                    $savedSection = $existing;
+                } else {
+                    $savedSection = DocumentTemplateSection::create(array_merge(
+                        ['template_id' => $template->id],
+                        $sectionData
+                    ));
+                }
+
+                // 섹션 항목 upsert
+                if (isset($section['items'])) {
+                    $itemIncomingIds = collect($section['items'])->pluck('id')->filter()->toArray();
+                    $savedSection->items()->whereNotIn('id', $itemIncomingIds)->delete();
 
-                if (! empty($section['items'])) {
                     foreach ($section['items'] as $iIndex => $item) {
-                        DocumentTemplateSectionItem::create([
-                            'section_id' => $newSection->id,
+                        $itemData = [
                             'category' => $item['category'] ?? '',
                             'item' => $item['item'] ?? '',
                             'standard' => $item['standard'] ?? '',
@@ -688,24 +709,46 @@ private function saveRelations(DocumentTemplate $template, array $data, bool $de
                             'regulation' => $item['regulation'] ?? '',
                             'field_values' => $item['field_values'] ?? null,
                             'sort_order' => $iIndex,
-                        ]);
+                        ];
+
+                        if (! empty($item['id']) && $savedSection->items()->where('id', $item['id'])->exists()) {
+                            $savedSection->items()->where('id', $item['id'])->update($itemData);
+                        } else {
+                            DocumentTemplateSectionItem::create(array_merge(
+                                ['section_id' => $savedSection->id],
+                                $itemData
+                            ));
+                        }
                     }
                 }
             }
         }
 
-        // 컬럼
-        if (! empty($data['columns'])) {
+        // 컬럼: ID 보존 upsert (document_data.column_id 참조 보호)
+        if (isset($data['columns'])) {
+            $incomingIds = collect($data['columns'])->pluck('id')->filter()->toArray();
+            if ($deleteExisting) {
+                $template->columns()->whereNotIn('id', $incomingIds)->delete();
+            }
+
             foreach ($data['columns'] as $index => $column) {
-                DocumentTemplateColumn::create([
-                    'template_id' => $template->id,
+                $colData = [
                     'label' => $column['label'] ?? '',
                     'width' => $column['width'] ?? '100px',
                     'column_type' => $column['column_type'] ?? 'text',
                     'group_name' => $column['group_name'] ?? null,
                     'sub_labels' => $column['sub_labels'] ?? null,
                     'sort_order' => $index,
-                ]);
+                ];
+
+                if (! empty($column['id']) && $template->columns()->where('id', $column['id'])->exists()) {
+                    $template->columns()->where('id', $column['id'])->update($colData);
+                } else {
+                    DocumentTemplateColumn::create(array_merge(
+                        ['template_id' => $template->id],
+                        $colData
+                    ));
+                }
             }
         }