diff --git a/locales/en-US.yml b/locales/en-US.yml
index c202d53d1..da49a6094 100644
--- a/locales/en-US.yml
+++ b/locales/en-US.yml
@@ -528,6 +528,7 @@ mediaListWithOneImageAppearance: "Height of media lists with one image only"
 limitTo: "Limit to {x}"
 noFollowRequests: "You don't have any pending follow requests"
 openImageInNewTab: "Open images in new tab"
+warnForMissingAltText: "Warn you when you forget to put alt text"
 dashboard: "Dashboard"
 local: "Local"
 remote: "Remote"
@@ -1045,6 +1046,9 @@ thisPostMayBeAnnoying: "This note may annoy others."
 thisPostMayBeAnnoyingHome: "Post to home timeline"
 thisPostMayBeAnnoyingCancel: "Cancel"
 thisPostMayBeAnnoyingIgnore: "Post anyway"
+thisPostIsMissingAltTextCancel: "Cancel"
+thisPostIsMissingAltTextIgnore: "Post anyway"
+thisPostIsMissingAltText: "One of the files attached to this post is missing alt text. Please ensure all the attachments have alt text."
 collapseRenotes: "Collapse renotes you've already seen"
 internalServerError: "Internal Server Error"
 internalServerErrorDescription: "The server has run into an unexpected error."
diff --git a/locales/index.d.ts b/locales/index.d.ts
index 045db3c84..d52929c54 100644
--- a/locales/index.d.ts
+++ b/locales/index.d.ts
@@ -4207,6 +4207,18 @@ export interface Locale extends ILocale {
      * このまま投稿
      */
     "thisPostMayBeAnnoyingIgnore": string;
+    /**
+     * やめる
+     */
+    "thisPostIsMissingAltTextCancel": string;
+    /**
+     * このまま投稿
+     */
+    "thisPostIsMissingAltTextIgnore": string;
+    /**
+     * この投稿に添付されたファイルの 1 つに代替テキストがありません。すべての添付ファイルに代替テキストが含まれていることを確認してください。
+     */
+    "thisPostIsMissingAltText": string;
     /**
      * 見たことのあるリノートを省略して表示
      */
diff --git a/locales/ja-JP.yml b/locales/ja-JP.yml
index 7465bdbb0..c5db3bd21 100644
--- a/locales/ja-JP.yml
+++ b/locales/ja-JP.yml
@@ -1047,6 +1047,9 @@ thisPostMayBeAnnoying: "この投稿は迷惑になる可能性があります
 thisPostMayBeAnnoyingHome: "ホームに投稿"
 thisPostMayBeAnnoyingCancel: "やめる"
 thisPostMayBeAnnoyingIgnore: "このまま投稿"
+thisPostIsMissingAltTextCancel: "やめる"
+thisPostIsMissingAltTextIgnore: "このまま投稿"
+thisPostIsMissingAltText: "この投稿に添付されたファイルの 1 つに代替テキストがありません。すべての添付ファイルに代替テキストが含まれていることを確認してください。"
 collapseRenotes: "見たことのあるリノートを省略して表示"
 internalServerError: "サーバー内部エラー"
 internalServerErrorDescription: "サーバー内部で予期しないエラーが発生しました。"
diff --git a/packages/frontend/src/components/MkPostForm.vue b/packages/frontend/src/components/MkPostForm.vue
index 00e5f3966..27dc8a5f4 100644
--- a/packages/frontend/src/components/MkPostForm.vue
+++ b/packages/frontend/src/components/MkPostForm.vue
@@ -101,7 +101,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 </template>
 
 <script lang="ts" setup>
-import { inject, watch, nextTick, onMounted, onUnmounted, defineAsyncComponent, provide, shallowRef, ref, computed } from 'vue';
+import { inject, watch, nextTick, onMounted, onUnmounted, defineAsyncComponent, provide, shallowRef, ref, computed, toRaw } from 'vue';
 import * as mfm from 'mfm-js';
 import * as Misskey from 'misskey-js';
 import insertTextAtCursor from 'insert-text-at-cursor';
@@ -760,6 +760,31 @@ async function post(ev?: MouseEvent) {
 		}
 	}
 
+	if (defaultStore.state.warnMissingAltText) {
+		const filesData = toRaw(files.value);
+
+		const isMissingAltText = filesData.filter(
+			file => file.type.startsWith('image/') || file.type.startsWith('video/') || file.type.startsWith('audio/'),
+		).some(file => !file.comment);
+
+		if (isMissingAltText) {
+			const { canceled, result } = await os.actions({
+				type: 'warning',
+				text: i18n.ts.thisPostIsMissingAltText,
+				actions: [{
+					value: 'cancel',
+					text: i18n.ts.thisPostIsMissingAltTextCancel,
+				}, {
+					value: 'ignore',
+					text: i18n.ts.thisPostIsMissingAltTextIgnore,
+				}],
+			});
+
+			if (canceled) return;
+			if (result === 'cancel') return;
+		}
+	}
+
 	let postData = {
 		text: text.value === '' ? null : text.value,
 		// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
@@ -874,9 +899,9 @@ async function post(ev?: MouseEvent) {
 			type: 'error',
 			text: err.message + '\n' + (err as any).id,
 		});
-		emit("postError");
+		emit('postError');
 	});
-	emit("posting");
+	emit('posting');
 }
 
 function cancel() {
@@ -893,7 +918,7 @@ async function insertEmoji(ev: MouseEvent) {
 	os.openEmojiPicker(
 		(ev.currentTarget ?? ev.target) as HTMLElement,
 		{ asReactionPicker: false },
-		textareaEl.value
+		textareaEl.value,
 	);
 }
 
diff --git a/packages/frontend/src/pages/settings/general.vue b/packages/frontend/src/pages/settings/general.vue
index db7d5ddcf..172e07001 100644
--- a/packages/frontend/src/pages/settings/general.vue
+++ b/packages/frontend/src/pages/settings/general.vue
@@ -162,6 +162,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 		<div class="_gaps_m">
 			<div class="_gaps_s">
+				<MkSwitch v-model="warnMissingAltText">{{ i18n.ts.warnForMissingAltText }}</MkSwitch>
 				<MkSwitch v-model="imageNewTab">{{ i18n.ts.openImageInNewTab }}</MkSwitch>
 				<MkSwitch v-model="useReactionPickerForContextMenu">{{ i18n.ts.useReactionPickerForContextMenu }}</MkSwitch>
 				<MkSwitch v-model="enableInfiniteScroll">{{ i18n.ts.enableInfiniteScroll }}</MkSwitch>
@@ -299,6 +300,7 @@ const forceShowAds = computed(defaultStore.makeGetterSetter('forceShowAds'));
 const loadRawImages = computed(defaultStore.makeGetterSetter('loadRawImages'));
 const highlightSensitiveMedia = computed(defaultStore.makeGetterSetter('highlightSensitiveMedia'));
 const imageNewTab = computed(defaultStore.makeGetterSetter('imageNewTab'));
+const warnMissingAltText = computed(defaultStore.makeGetterSetter('warnMissingAltText'));
 const nsfw = computed(defaultStore.makeGetterSetter('nsfw'));
 const showFixedPostForm = computed(defaultStore.makeGetterSetter('showFixedPostForm'));
 const showFixedPostFormInChannel = computed(defaultStore.makeGetterSetter('showFixedPostFormInChannel'));
diff --git a/packages/frontend/src/pages/settings/preferences-backups.vue b/packages/frontend/src/pages/settings/preferences-backups.vue
index da6fb5f6b..58380c361 100644
--- a/packages/frontend/src/pages/settings/preferences-backups.vue
+++ b/packages/frontend/src/pages/settings/preferences-backups.vue
@@ -75,6 +75,7 @@ const defaultStoreSaveKeys: (keyof typeof defaultStore['state'])[] = [
 	'showRenotesCount',
 	'showReactionsCount',
 	'loadRawImages',
+	'warnMissingAltText',
 	'imageNewTab',
 	'dataSaver',
 	'disableShowingAnimatedImages',
diff --git a/packages/frontend/src/store.ts b/packages/frontend/src/store.ts
index 81b21dd5e..b44e1d9c4 100644
--- a/packages/frontend/src/store.ts
+++ b/packages/frontend/src/store.ts
@@ -247,6 +247,10 @@ export const defaultStore = markRaw(new Storage('base', {
 		where: 'device',
 		default: false,
 	},
+	warnMissingAltText: {
+		where: 'device',
+		default: true,
+	},
 	imageNewTab: {
 		where: 'device',
 		default: false,