diff --git a/src/client/app/desktop/views/components/settings.vue b/src/client/app/desktop/views/components/settings.vue
index 1a8cb6b0b9..50582b3525 100644
--- a/src/client/app/desktop/views/components/settings.vue
+++ b/src/client/app/desktop/views/components/settings.vue
@@ -169,6 +169,9 @@
 					%i18n:@auto-watch%
 					<span slot="desc">%i18n:@auto-watch-desc%</span>
 				</ui-switch>
+				<section>
+					<ui-button @click="readAllUnreadNotes">%i18n:@mark-as-read-all-unread-notes%</ui-button>
+				</section>
 			</section>
 		</ui-card>
 
@@ -488,6 +491,9 @@ export default Vue.extend({
 		});
 	},
 	methods: {
+		readAllUnreadNotes() {
+			(this as any).api('i/read_all_unread_notes');
+		},
 		customizeHome() {
 			this.$router.push('/i/customize-home');
 			this.$emit('done');
diff --git a/src/server/api/endpoints/i/read_all_unread_notes.ts b/src/server/api/endpoints/i/read_all_unread_notes.ts
new file mode 100644
index 0000000000..fae98b9816
--- /dev/null
+++ b/src/server/api/endpoints/i/read_all_unread_notes.ts
@@ -0,0 +1,36 @@
+import User, { ILocalUser } from '../../../../models/user';
+import { publishMainStream } from '../../../../stream';
+import NoteUnread from '../../../../models/note-unread';
+
+export const meta = {
+	desc: {
+		'ja-JP': '未読の投稿をすべて既読にします。'
+	},
+
+	requireCredential: true,
+
+	kind: 'account-write',
+
+	params: {
+	}
+};
+
+export default async (params: any, user: ILocalUser) => new Promise(async (res, rej) => {
+	// Remove documents
+	await NoteUnread.remove({
+		userId: user._id
+	});
+
+	User.update({ _id: user._id }, {
+		$set: {
+			hasUnreadMentions: false,
+			hasUnreadSpecifiedNotes: false
+		}
+	});
+
+	// 全て既読になったイベントを発行
+	publishMainStream(user._id, 'readAllUnreadMentions');
+	publishMainStream(user._id, 'readAllUnreadSpecifiedNotes');
+
+	res();
+});