diff --git a/CHANGELOG.md b/CHANGELOG.md
index e8909c15d..36645aff7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@
 -
 
 ### Client
--
+- メールアドレス不要でCaptchaが有効な場合にアカウント登録完了後自動でのログインに失敗する問題を修正
 
 ### Server
 -
diff --git a/packages/frontend/src/account.ts b/packages/frontend/src/account.ts
index 84d89b1b3..b91834b94 100644
--- a/packages/frontend/src/account.ts
+++ b/packages/frontend/src/account.ts
@@ -226,7 +226,7 @@ export async function openAccountMenu(opts: {
 
 	function showSigninDialog() {
 		const { dispose } = popup(defineAsyncComponent(() => import('@/components/MkSigninDialog.vue')), {}, {
-			done: res => {
+			done: (res: Misskey.entities.SigninFlowResponse & { finished: true }) => {
 				addAccount(res.id, res.i);
 				success();
 			},
@@ -236,9 +236,9 @@ export async function openAccountMenu(opts: {
 
 	function createAccount() {
 		const { dispose } = popup(defineAsyncComponent(() => import('@/components/MkSignupDialog.vue')), {}, {
-			done: res => {
-				addAccount(res.id, res.i);
-				switchAccountWithToken(res.i);
+			done: (res: Misskey.entities.SignupResponse) => {
+				addAccount(res.id, res.token);
+				switchAccountWithToken(res.token);
 			},
 			closed: () => dispose(),
 		});
diff --git a/packages/frontend/src/components/MkSignin.vue b/packages/frontend/src/components/MkSignin.vue
index a79d7cf07..a773cefda 100644
--- a/packages/frontend/src/components/MkSignin.vue
+++ b/packages/frontend/src/components/MkSignin.vue
@@ -83,7 +83,7 @@ import type { AuthenticationPublicKeyCredential } from '@github/webauthn-json/br
 import type { OpenOnRemoteOptions } from '@/scripts/please-login.js';
 
 const emit = defineEmits<{
-	(ev: 'login', v: Misskey.entities.SigninFlowResponse): void;
+	(ev: 'login', v: Misskey.entities.SigninFlowResponse & { finished: true }): void;
 }>();
 
 const props = withDefaults(defineProps<{
@@ -276,7 +276,7 @@ async function tryLogin(req: Partial<Misskey.entities.SigninFlowRequest>): Promi
 	});
 }
 
-async function onLoginSucceeded(res: Misskey.entities.SigninFlowResponse & { finished: true; }) {
+async function onLoginSucceeded(res: Misskey.entities.SigninFlowResponse & { finished: true }) {
 	if (props.autoSet) {
 		await login(res.i);
 	}
diff --git a/packages/frontend/src/components/MkSigninDialog.vue b/packages/frontend/src/components/MkSigninDialog.vue
index 2aa11ac31..51dea960a 100644
--- a/packages/frontend/src/components/MkSigninDialog.vue
+++ b/packages/frontend/src/components/MkSigninDialog.vue
@@ -23,6 +23,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 </template>
 
 <script lang="ts" setup>
+import * as Misskey from 'misskey-js';
 import { shallowRef } from 'vue';
 import type { OpenOnRemoteOptions } from '@/scripts/please-login.js';
 import MkSignin from '@/components/MkSignin.vue';
@@ -40,7 +41,7 @@ withDefaults(defineProps<{
 });
 
 const emit = defineEmits<{
-	(ev: 'done', v: any): void;
+	(ev: 'done', v: Misskey.entities.SigninFlowResponse & { finished: true }): void;
 	(ev: 'closed'): void;
 	(ev: 'cancelled'): void;
 }>();
@@ -52,7 +53,7 @@ function onClose() {
 	if (modal.value) modal.value.close();
 }
 
-function onLogin(res) {
+function onLogin(res: Misskey.entities.SigninFlowResponse & { finished: true }) {
 	emit('done', res);
 	if (modal.value) modal.value.close();
 }
diff --git a/packages/frontend/src/components/MkSignupDialog.form.vue b/packages/frontend/src/components/MkSignupDialog.form.vue
index a0c548898..ffb5551ff 100644
--- a/packages/frontend/src/components/MkSignupDialog.form.vue
+++ b/packages/frontend/src/components/MkSignupDialog.form.vue
@@ -98,7 +98,7 @@ const props = withDefaults(defineProps<{
 });
 
 const emit = defineEmits<{
-	(ev: 'signup', user: Misskey.entities.SigninFlowResponse): void;
+	(ev: 'signup', user: Misskey.entities.SignupResponse): void;
 	(ev: 'signupEmailPending'): void;
 }>();
 
@@ -250,18 +250,30 @@ async function onSubmit(): Promise<void> {
 	if (submitting.value) return;
 	submitting.value = true;
 
-	try {
-		await misskeyApi('signup', {
-			username: username.value,
-			password: password.value,
-			emailAddress: email.value,
-			invitationCode: invitationCode.value,
-			'hcaptcha-response': hCaptchaResponse.value,
-			'm-captcha-response': mCaptchaResponse.value,
-			'g-recaptcha-response': reCaptchaResponse.value,
-			'turnstile-response': turnstileResponse.value,
-		});
-		if (instance.emailRequiredForSignup) {
+	const signupPayload: Misskey.entities.SignupRequest = {
+		username: username.value,
+		password: password.value,
+		emailAddress: email.value,
+		invitationCode: invitationCode.value,
+		'hcaptcha-response': hCaptchaResponse.value,
+		'm-captcha-response': mCaptchaResponse.value,
+		'g-recaptcha-response': reCaptchaResponse.value,
+		'turnstile-response': turnstileResponse.value,
+	};
+
+	const res = await fetch(`${config.apiUrl}/signup`, {
+		method: 'POST',
+		headers: {
+			'Content-Type': 'application/json',
+		},
+		body: JSON.stringify(signupPayload),
+	}).catch(() => {
+		onSignupApiError();
+		return null;
+	});
+
+	if (res) {
+		if (res.status === 204 || instance.emailRequiredForSignup) {
 			os.alert({
 				type: 'success',
 				title: i18n.ts._signup.almostThere,
@@ -269,33 +281,31 @@ async function onSubmit(): Promise<void> {
 			});
 			emit('signupEmailPending');
 		} else {
-			const res = await misskeyApi('signin-flow', {
-				username: username.value,
-				password: password.value,
-			});
-			emit('signup', res);
+			const resJson = (await res.json()) as Misskey.entities.SignupResponse;
+			if (_DEV_) console.log(resJson);
 
-			if (props.autoSet && res.finished) {
-				return login(res.i);
-			} else {
-				os.alert({
-					type: 'error',
-					text: i18n.ts.somethingHappened,
-				});
+			emit('signup', resJson);
+
+			if (props.autoSet) {
+				await login(resJson.token);
 			}
 		}
-	} catch {
-		submitting.value = false;
-		hcaptcha.value?.reset?.();
-		mcaptcha.value?.reset?.();
-		recaptcha.value?.reset?.();
-		turnstile.value?.reset?.();
-
-		os.alert({
-			type: 'error',
-			text: i18n.ts.somethingHappened,
-		});
 	}
+
+	submitting.value = false;
+}
+
+function onSignupApiError() {
+	submitting.value = false;
+	hcaptcha.value?.reset?.();
+	mcaptcha.value?.reset?.();
+	recaptcha.value?.reset?.();
+	turnstile.value?.reset?.();
+
+	os.alert({
+		type: 'error',
+		text: i18n.ts.somethingHappened,
+	});
 }
 </script>
 
diff --git a/packages/frontend/src/components/MkSignupDialog.vue b/packages/frontend/src/components/MkSignupDialog.vue
index 4cccd9949..f240e6dc4 100644
--- a/packages/frontend/src/components/MkSignupDialog.vue
+++ b/packages/frontend/src/components/MkSignupDialog.vue
@@ -47,7 +47,7 @@ const props = withDefaults(defineProps<{
 });
 
 const emit = defineEmits<{
-	(ev: 'done', res: Misskey.entities.SigninFlowResponse): void;
+	(ev: 'done', res: Misskey.entities.SignupResponse): void;
 	(ev: 'closed'): void;
 }>();
 
@@ -55,7 +55,7 @@ const dialog = shallowRef<InstanceType<typeof MkModalWindow>>();
 
 const isAcceptedServerRule = ref(false);
 
-function onSignup(res: Misskey.entities.SigninFlowResponse) {
+function onSignup(res: Misskey.entities.SignupResponse) {
 	emit('done', res);
 	dialog.value?.close();
 }
diff --git a/packages/frontend/src/components/MkUserCardMini.vue b/packages/frontend/src/components/MkUserCardMini.vue
index b333722dc..7a2e87893 100644
--- a/packages/frontend/src/components/MkUserCardMini.vue
+++ b/packages/frontend/src/components/MkUserCardMini.vue
@@ -23,7 +23,7 @@ import { acct } from '@/filters/user.js';
 
 const props = withDefaults(defineProps<{
 	user: Misskey.entities.User;
-	withChart: boolean;
+	withChart?: boolean;
 }>(), {
 	withChart: true,
 });
diff --git a/packages/frontend/src/pages/settings/accounts.vue b/packages/frontend/src/pages/settings/accounts.vue
index 08c9261dc..1bbedb817 100644
--- a/packages/frontend/src/pages/settings/accounts.vue
+++ b/packages/frontend/src/pages/settings/accounts.vue
@@ -45,7 +45,7 @@ const init = async () => {
 	});
 };
 
-function menu(account, ev) {
+function menu(account: Misskey.entities.UserDetailed, ev: MouseEvent) {
 	os.popupMenu([{
 		text: i18n.ts.switch,
 		icon: 'ti ti-switch-horizontal',
@@ -58,7 +58,7 @@ function menu(account, ev) {
 	}], ev.currentTarget ?? ev.target);
 }
 
-function addAccount(ev) {
+function addAccount(ev: MouseEvent) {
 	os.popupMenu([{
 		text: i18n.ts.existingAccount,
 		action: () => { addExistingAccount(); },
@@ -68,14 +68,14 @@ function addAccount(ev) {
 	}], ev.currentTarget ?? ev.target);
 }
 
-async function removeAccount(account) {
+async function removeAccount(account: Misskey.entities.UserDetailed) {
 	await _removeAccount(account.id);
 	accounts.value = accounts.value.filter(x => x.id !== account.id);
 }
 
 function addExistingAccount() {
 	const { dispose } = os.popup(defineAsyncComponent(() => import('@/components/MkSigninDialog.vue')), {}, {
-		done: async res => {
+		done: async (res: Misskey.entities.SigninFlowResponse & { finished: true }) => {
 			await addAccounts(res.id, res.i);
 			os.success();
 			init();
@@ -86,17 +86,17 @@ function addExistingAccount() {
 
 function createAccount() {
 	const { dispose } = os.popup(defineAsyncComponent(() => import('@/components/MkSignupDialog.vue')), {}, {
-		done: async res => {
-			await addAccounts(res.id, res.i);
-			switchAccountWithToken(res.i);
+		done: async (res: Misskey.entities.SignupResponse) => {
+			await addAccounts(res.id, res.token);
+			switchAccountWithToken(res.token);
 		},
 		closed: () => dispose(),
 	});
 }
 
 async function switchAccount(account: any) {
-	const fetchedAccounts: any[] = await getAccounts();
-	const token = fetchedAccounts.find(x => x.id === account.id).token;
+	const fetchedAccounts = await getAccounts();
+	const token = fetchedAccounts.find(x => x.id === account.id)!.token;
 	switchAccountWithToken(token);
 }
 
diff --git a/packages/misskey-js/etc/misskey-js.api.md b/packages/misskey-js/etc/misskey-js.api.md
index 1da8e4e61..72c236373 100644
--- a/packages/misskey-js/etc/misskey-js.api.md
+++ b/packages/misskey-js/etc/misskey-js.api.md
@@ -3095,7 +3095,9 @@ type SigninWithPasskeyRequest = {
 
 // @public (undocumented)
 type SigninWithPasskeyResponse = {
-    signinResponse: SigninFlowResponse;
+    signinResponse: SigninFlowResponse & {
+        finished: true;
+    };
 };
 
 // @public (undocumented)
diff --git a/packages/misskey-js/src/entities.ts b/packages/misskey-js/src/entities.ts
index 2ffee40fb..dd88791ed 100644
--- a/packages/misskey-js/src/entities.ts
+++ b/packages/misskey-js/src/entities.ts
@@ -308,7 +308,7 @@ export type SigninWithPasskeyInitResponse = {
 };
 
 export type SigninWithPasskeyResponse = {
-	signinResponse: SigninFlowResponse;
+	signinResponse: SigninFlowResponse & { finished: true };
 };
 
 type Values<T extends Record<PropertyKey, unknown>> = T[keyof T];