diff --git a/CHANGELOG.md b/CHANGELOG.md
index 42b132089..82822c903 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,7 @@
 - Enhance: 未読の通知数を表示できるように
 - Enhance: ローカリゼーションの更新
 - Enhance: 依存関係の更新
+- Change: CWを使用する場合、注釈を空にすることは許可されなくなりました
 
 ### Client
 - Feat: プラグイン・テーマを外部サイトから直接インストールできるようになりました
diff --git a/locales/index.d.ts b/locales/index.d.ts
index eb2798308..b8dc3a68b 100644
--- a/locales/index.d.ts
+++ b/locales/index.d.ts
@@ -1158,6 +1158,7 @@ export interface Locale {
     "pullDownToRefresh": string;
     "disableStreamingTimeline": string;
     "useGroupedNotifications": string;
+    "cwNotationRequired": string;
     "_announcement": {
         "forExistingUsers": string;
         "forExistingUsersDescription": string;
diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index 4af21ab52..76b5386b3 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -1155,6 +1155,7 @@ refreshing: "リロード中"
 pullDownToRefresh: "引っ張ってリロード"
 disableStreamingTimeline: "タイムラインのリアルタイム更新を無効にする"
 useGroupedNotifications: "通知をグルーピングして表示する"
+cwNotationRequired: "「内容を隠す」がオンの場合は注釈の記述が必要です。"
 
 _announcement:
   forExistingUsers: "既存ユーザーのみ"
diff --git a/packages/backend/src/server/api/endpoints/notes/create.ts b/packages/backend/src/server/api/endpoints/notes/create.ts
index 649068fb2..fb650f69f 100644
--- a/packages/backend/src/server/api/endpoints/notes/create.ts
+++ b/packages/backend/src/server/api/endpoints/notes/create.ts
@@ -16,8 +16,8 @@ import { Endpoint } from '@/server/api/endpoint-base.js';
 import { NoteEntityService } from '@/core/entities/NoteEntityService.js';
 import { NoteCreateService } from '@/core/NoteCreateService.js';
 import { DI } from '@/di-symbols.js';
-import { ApiError } from '../../error.js';
 import { isPureRenote } from '@/misc/is-pure-renote.js';
+import { ApiError } from '../../error.js';
 
 export const meta = {
 	tags: ['notes'],
@@ -109,7 +109,7 @@ export const paramDef = {
 		visibleUserIds: { type: 'array', uniqueItems: true, items: {
 			type: 'string', format: 'misskey:id',
 		} },
-		cw: { type: 'string', nullable: true, maxLength: 100 },
+		cw: { type: 'string', nullable: true, minLength: 1, maxLength: 100 },
 		localOnly: { type: 'boolean', default: false },
 		reactionAcceptance: { type: 'string', nullable: true, enum: [null, 'likeOnly', 'likeOnlyForRemote', 'nonSensitiveOnly', 'nonSensitiveOnlyForLocalLikeOnlyForRemote'], default: null },
 		noExtractMentions: { type: 'boolean', default: false },
diff --git a/packages/frontend/src/components/MkPostForm.vue b/packages/frontend/src/components/MkPostForm.vue
index 598846b16..1fa568586 100644
--- a/packages/frontend/src/components/MkPostForm.vue
+++ b/packages/frontend/src/components/MkPostForm.vue
@@ -658,6 +658,14 @@ function deleteDraft() {
 }
 
 async function post(ev?: MouseEvent) {
+	if (useCw && (cw == null || cw.trim() === '')) {
+		os.alert({
+			type: 'error',
+			text: i18n.ts.cwNotationRequired,
+		});
+		return;
+	}
+
 	if (ev) {
 		const el = ev.currentTarget ?? ev.target;
 		const rect = el.getBoundingClientRect();