diff --git a/backend/src/modules/task/task.service.ts b/backend/src/modules/task/task.service.ts
index 06101be..43f6919 100644
--- a/backend/src/modules/task/task.service.ts
+++ b/backend/src/modules/task/task.service.ts
@@ -1383,7 +1383,12 @@ export class TaskService {
         c.workStatus = ws;
         changed.push(c);
       }
-      return { itemId: c.id, text: c.text, category: c.category, workStatus: ws };
+      return {
+        itemId: c.id,
+        text: c.text,
+        category: c.category,
+        workStatus: ws,
+      };
     });
     if (changed.length) {
       await this.checklistRepo.save(changed);
@@ -1429,8 +1434,19 @@ export class TaskService {
     const existingTimes = existing.map((c) => c.checkAt.getTime());
     const wantedTimes = [...new Set(dates.map((d) => new Date(d).getTime()))];
 
+    // 보고가 있는 점검일은 삭제하지 않는다 — 보고 이력(스냅샷) 보존
+    // (점검일 삭제 시 checkpoint_reports 가 CASCADE 로 함께 사라지므로 명시적으로 보호)
+    const reports = await this.reportRepo.find({
+      where: { task: { id: task.id } },
+      relations: ['checkpoint'],
+    });
+    const reportedIds = new Set(
+      reports.map((r) => r.checkpoint?.id).filter((id): id is string => !!id),
+    );
+
     const toRemove = existing.filter(
-      (c) => !wantedTimes.includes(c.checkAt.getTime()),
+      (c) =>
+        !wantedTimes.includes(c.checkAt.getTime()) && !reportedIds.has(c.id),
     );
     if (toRemove.length) {
       await this.checkpointRepo.remove(toRemove);
diff --git a/frontend/src/pages/relay/TaskCreatePage.vue b/frontend/src/pages/relay/TaskCreatePage.vue
index 8f73345..af20acf 100644
--- a/frontend/src/pages/relay/TaskCreatePage.vue
+++ b/frontend/src/pages/relay/TaskCreatePage.vue
@@ -100,6 +100,13 @@ async function loadTaskForEdit() {
     }))
     existingFiles.value = t.files
     checkpoints.value = t.checkpoints.map((c) => toDateInput(c.checkAt)).sort()
+    // 보고가 접수된 점검일은 잠금(삭제 불가) — 보고 이력 보존
+    const reportedCpIds = new Set(t.checkpointReports.map((r) => r.checkpointId))
+    reportedCheckpointDates.value = new Set(
+      t.checkpoints
+        .filter((c) => reportedCpIds.has(c.id))
+        .map((c) => toDateInput(c.checkAt)),
+    )
   } catch {
     // 404 등은 인터셉터가 알림 처리
   }
@@ -163,6 +170,8 @@ const dueDate = ref('') // yyyy-MM-dd (input[type=date])
 // --- 중간 점검일(여러 개) — 작업자가 진행 상태를 보고하는 기준일 ---
 const checkpoints = ref<string[]>([]) // yyyy-MM-dd 목록
 const newCheckpoint = ref('')
+// 이미 보고가 접수된 점검일(yyyy-MM-dd) — 삭제 불가(보고 이력 보존)
+const reportedCheckpointDates = ref<Set<string>>(new Set())
 function addCheckpoint() {
   const d = newCheckpoint.value
   if (!d) return
@@ -173,6 +182,8 @@ function addCheckpoint() {
   newCheckpoint.value = ''
 }
 function removeCheckpoint(d: string) {
+  // 보고가 접수된 날짜는 삭제하지 않는다(서버도 거부/보존)
+  if (reportedCheckpointDates.value.has(d)) return
   checkpoints.value = checkpoints.value.filter((x) => x !== d)
 }
 
@@ -1081,7 +1092,13 @@ function goBack() {
                   class="cp-item"
                 >
                   <span>{{ d }}</span>
+                  <span
+                    v-if="reportedCheckpointDates.has(d)"
+                    class="cp-locked"
+                    title="보고가 접수되어 삭제할 수 없습니다"
+                  >보고됨</span>
                   <button
+                    v-else
                     class="x"
                     type="button"
                     title="삭제"
@@ -2259,6 +2276,14 @@ function goBack() {
   line-height: 1;
   padding: 0 0.25rem;
 }
+.cp-locked {
+  font-size: 0.6875rem;
+  font-weight: 700;
+  color: #1b7a3d;
+  background: var(--green-weak);
+  padding: 0.0625rem 0.4375rem;
+  border-radius: 20px;
+}
 .cp-item .x:hover {
   color: var(--red);
 }