diff --git a/backend-node/src/controllers/salesEstimateController.ts b/backend-node/src/controllers/salesEstimateController.ts
index 6467ebd2..a28df17f 100644
--- a/backend-node/src/controllers/salesEstimateController.ts
+++ b/backend-node/src/controllers/salesEstimateController.ts
@@ -68,7 +68,8 @@ export async function remove(req: AuthenticatedRequest, res: Response) {
     return res.json({ success: true, message: "견적이 삭제되었습니다." });
   } catch (error: any) {
     logger.error("견적 삭제 실패", { error: error.message });
-    return res.status(500).json({ success: false, message: error.message });
+    // AppError(statusCode) 우선 — G8 guard 409 등
+    return res.status(error?.statusCode ?? 500).json({ success: false, message: error.message });
   }
 }
 
diff --git a/backend-node/src/controllers/salesOrderMgmtController.ts b/backend-node/src/controllers/salesOrderMgmtController.ts
index d086fbe3..831813db 100644
--- a/backend-node/src/controllers/salesOrderMgmtController.ts
+++ b/backend-node/src/controllers/salesOrderMgmtController.ts
@@ -49,7 +49,11 @@ export async function remove(req: AuthenticatedRequest, res: Response) {
     const { id } = req.params;
     await svc.remove(id);
     return res.json({ success: true, message: "주문서가 삭제되었습니다." });
-  } catch (e: any) { logger.error("주문서 삭제 실패", { error: e.message }); return res.status(500).json({ success: false, message: e.message }); }
+  } catch (e: any) {
+    logger.error("주문서 삭제 실패", { error: e.message });
+    // AppError(statusCode) 우선 — G8 guard 409 등
+    return res.status(e?.statusCode ?? 500).json({ success: false, message: e.message });
+  }
 }
 
 export async function getFormView(req: AuthenticatedRequest, res: Response) {
diff --git a/backend-node/src/services/salesEstimateService.ts b/backend-node/src/services/salesEstimateService.ts
index 7d630439..0d1376a8 100644
--- a/backend-node/src/services/salesEstimateService.ts
+++ b/backend-node/src/services/salesEstimateService.ts
@@ -10,7 +10,7 @@ import { PDFDocument } from "pdf-lib";
 import { getPool } from "../database/db";
 import { logger } from "../utils/logger";
 import { sendMailUTF8 } from "../utils/mailUtil";
-import { generateContractNo } from "./salesOrderMgmtService";
+import { generateContractNo, assertNoProjectExists } from "./salesOrderMgmtService";
 
 // ─── 타입 ─────────────────────────────────────────────────────
 
@@ -837,13 +837,16 @@ function textToHtml(text: string): string {
 
 // ─── 삭제 ─────────────────────────────────────────────────────
 // 시리얼 → 라인 → 헤더(contract_mgmt) 순.
-// (G8 — 프로젝트 존재 시 삭제 방지는 별도 PR)
+// G8 — 프로젝트가 생성된 건은 삭제 차단 (wace ContractMgmtService.deleteContractMngInfo:794-808 동일).
+//      helper는 project_mgmt 도메인 주인인 salesOrderMgmtService에 정의 (assertNoProjectExists).
 
 export async function remove(objid: string) {
   const pool = getPool();
   const client = await pool.connect();
   try {
     await client.query("BEGIN");
+    // G8 guard
+    await assertNoProjectExists(client, objid);
     await client.query(
       `UPDATE contract_item_serial SET status='INACTIVE'
         WHERE item_objid IN (SELECT objid FROM contract_item WHERE contract_objid=$1)`,
diff --git a/backend-node/src/services/salesOrderMgmtService.ts b/backend-node/src/services/salesOrderMgmtService.ts
index e6d84cc3..305d1d38 100644
--- a/backend-node/src/services/salesOrderMgmtService.ts
+++ b/backend-node/src/services/salesOrderMgmtService.ts
@@ -8,6 +8,7 @@
 
 import { getPool } from "../database/db";
 import { logger } from "../utils/logger";
+import { AppError } from "../middleware/errorHandler";
 
 export interface OrderListFilter {
   category_cd?: string;
@@ -519,12 +520,38 @@ export async function update(userId: string, objid: string, body: OrderBody) {
   } finally { client.release(); }
 }
 
+// G8 — 프로젝트가 생성된 contract는 견적/주문 모두 삭제 차단.
+// wace deleteContractMngInfo:794-808 + mapper getProjectListBycontractObjid:3909 1:1.
+// 원본 매퍼는 status 필터 없이 단순 contract_objid 매칭 → 그대로 따름.
+// salesEstimateService.remove에서도 import해서 사용.
+export async function assertNoProjectExists(client: any, contractObjid: string) {
+  const r = await client.query(
+    `SELECT 1 FROM project_mgmt WHERE contract_objid=$1 LIMIT 1`,
+    [contractObjid],
+  );
+  if (r.rowCount > 0) {
+    throw new AppError("프로젝트가 생성된 건은 삭제할 수 없습니다.", 409);
+  }
+}
+
 export async function remove(objid: string) {
   const pool = getPool();
-  await pool.query(`DELETE FROM contract_mgmt WHERE objid=$1`, [objid]);
-  // contract_item / contract_item_serial은 ON DELETE CASCADE 이지만,
-  // estimate_template (contract_objid 참조)는 FK가 없어 남을 수 있음 — 정책 결정 필요.
-  logger.info("주문서 삭제", { objid });
+  const client = await pool.connect();
+  try {
+    await client.query("BEGIN");
+    // G8 guard
+    await assertNoProjectExists(client, objid);
+    await client.query(`DELETE FROM contract_mgmt WHERE objid=$1`, [objid]);
+    await client.query("COMMIT");
+    // contract_item / contract_item_serial은 ON DELETE CASCADE.
+    // estimate_template (contract_objid 참조)는 FK 없어 남을 수 있음 — 별도 정책 결정 영역.
+    logger.info("주문서 삭제", { objid });
+  } catch (err) {
+    await client.query("ROLLBACK");
+    throw err;
+  } finally {
+    client.release();
+  }
 }
 
 // ─── 수주확정 → 프로젝트 자동생성 (wace ContractMgmtService.updateOrderStatus 이식) ──