diff --git a/app/Services/OrderService.php b/app/Services/OrderService.php
index 8eeb1eb4..59870222 100644
--- a/app/Services/OrderService.php
+++ b/app/Services/OrderService.php
@@ -1533,6 +1533,35 @@ public function createProductionOrder(int $orderId, array $data)
                 }
                 $itemsByProcess[$key]['items'][] = $orderItem;
             }
+
+            // 보조 공정(재고생산 등) 품목을 메인 공정으로 병합
+            $auxiliaryProcessIds = \App\Models\Process::where('tenant_id', $tenantId)
+                ->where('is_active', true)
+                ->get()
+                ->filter(fn ($p) => ! empty($p->options['is_auxiliary']))
+                ->pluck('id')
+                ->all();
+
+            $auxiliaryKeys = [];
+            $mainKeys = [];
+            foreach ($itemsByProcess as $key => $group) {
+                if ($key === 'none' || in_array($group['process_id'], $auxiliaryProcessIds, true)) {
+                    $auxiliaryKeys[] = $key;
+                } else {
+                    $mainKeys[] = $key;
+                }
+            }
+
+            if (! empty($auxiliaryKeys) && ! empty($mainKeys)) {
+                // 메인 공정 중 품목 수가 가장 많은 공정에 병합
+                $targetKey = collect($mainKeys)->sortByDesc(fn ($k) => count($itemsByProcess[$k]['items']))->first();
+                foreach ($auxiliaryKeys as $auxKey) {
+                    foreach ($itemsByProcess[$auxKey]['items'] as $item) {
+                        $itemsByProcess[$targetKey]['items'][] = $item;
+                    }
+                    unset($itemsByProcess[$auxKey]);
+                }
+            }
         }
 
         return DB::transaction(function () use ($order, $data, $tenantId, $userId, $itemsByProcess, $nodesBomMap, $isStock) {