diff --git a/packages/frontend/src/account.ts b/packages/frontend/src/account.ts
index a202a9aae9..634084c750 100644
--- a/packages/frontend/src/account.ts
+++ b/packages/frontend/src/account.ts
@@ -96,7 +96,6 @@ export async function removeAccount(idOrToken: Account['id']) {
 
 function fetchAccount(token: string, id?: string, forceShowDialog?: boolean): Promise<Account> {
 	return new Promise((done, fail) => {
-		// Fetch user
 		window.fetch(`${apiUrl}/i`, {
 			method: 'POST',
 			body: JSON.stringify({
diff --git a/packages/frontend/src/components/MkAnnouncementDialog.vue b/packages/frontend/src/components/MkAnnouncementDialog.vue
index b2e42e2f62..cd5a1a537f 100644
--- a/packages/frontend/src/components/MkAnnouncementDialog.vue
+++ b/packages/frontend/src/components/MkAnnouncementDialog.vue
@@ -28,6 +28,7 @@ import * as os from '@/os';
 import MkModal from '@/components/MkModal.vue';
 import MkButton from '@/components/MkButton.vue';
 import { i18n } from '@/i18n';
+import { $i, updateAccount } from '@/account';
 
 const props = withDefaults(defineProps<{
 	announcement: misskey.entities.Announcement;
@@ -40,6 +41,9 @@ const modal = shallowRef<InstanceType<typeof MkModal>>();
 function ok() {
 	modal.value.close();
 	os.api('i/read-announcement', { announcementId: props.announcement.id });
+	updateAccount({
+		unreadAnnouncements: $i!.unreadAnnouncements.filter(a => a.id !== props.announcement.id),
+	});
 }
 
 function onBgClick() {
diff --git a/packages/frontend/src/pages/announcements.vue b/packages/frontend/src/pages/announcements.vue
index bae95befe5..e6fa8a6b2e 100644
--- a/packages/frontend/src/pages/announcements.vue
+++ b/packages/frontend/src/pages/announcements.vue
@@ -34,7 +34,7 @@ import MkButton from '@/components/MkButton.vue';
 import * as os from '@/os';
 import { i18n } from '@/i18n';
 import { definePageMetadata } from '@/scripts/page-metadata';
-import { $i } from '@/account';
+import { $i, updateAccount } from '@/account';
 
 const pagination = {
 	endpoint: 'announcements' as const,
@@ -50,6 +50,9 @@ function read(id: string) {
 		return announcement;
 	});
 	os.api('i/read-announcement', { announcementId: id });
+	updateAccount({
+		unreadAnnouncements: $i!.unreadAnnouncements.filter(a => a.id !== id),
+	});
 }
 
 const headerActions = $computed(() => []);