diff --git a/src/client/components/captcha.vue b/src/client/components/captcha.vue
new file mode 100644
index 0000000000..6b1ee6f0b2
--- /dev/null
+++ b/src/client/components/captcha.vue
@@ -0,0 +1,119 @@
+<template>
+<div>
+	<span v-if="!available">{{ $t('waiting') }}<mk-ellipsis/></span>
+	<div ref="captcha"></div>
+</div>
+</template>
+
+<script lang="ts">
+import Vue from 'vue';
+import i18n from '../i18n';
+
+type Captcha = {
+	render(container: string | Node, options: {
+		readonly [_ in 'sitekey' | 'theme' | 'type' | 'size' | 'tabindex' | 'callback' | 'expired' | 'expired-callback' | 'error-callback' | 'endpoint']?: unknown;
+	}): string;
+	remove(id: string): void;
+	execute(id: string): void;
+	reset(id: string): void;
+	getResponse(id: string): string;
+};
+
+type CaptchaProvider = 'hcaptcha' | 'grecaptcha';
+
+type CaptchaContainer = {
+	readonly [_ in CaptchaProvider]?: Captcha;
+};
+
+declare global {
+	interface Window extends CaptchaContainer {
+	}
+}
+
+export default Vue.extend({
+	i18n,
+	props: {
+		provider: {
+			type: String,
+			required: true,
+		},
+		sitekey: {
+			type: String,
+			required: true,
+		},
+		value: {
+			type: String,
+		},
+	},
+
+	data() {
+		return {
+			available: false,
+		};
+	},
+
+	computed: {
+		loaded() {
+			return !!window[this.provider as CaptchaProvider];
+		},
+		src() {
+			const endpoint = ({
+				hcaptcha: 'https://hcaptcha.com/1',
+				grecaptcha: 'https://www.google.com/recaptcha',
+			} as Record<PropertyKey, unknown>)[this.provider];
+
+			return `${typeof endpoint == 'string' ? endpoint : 'about:invalid'}/api.js?render=explicit`;
+		},
+		captcha() {
+			return window[this.provider as CaptchaProvider] || {} as unknown as Captcha;
+		},
+	},
+
+	created() {
+		if (this.loaded) {
+			this.available = true;
+		} else {
+			(document.getElementById(this.provider) || document.head.appendChild(Object.assign(document.createElement('script'), {
+				async: true,
+				id: this.provider,
+				src: this.src,
+			})))
+				.addEventListener('load', () => this.available = true);
+		}
+	},
+
+	mounted() {
+		if (this.available) {
+			this.requestRender();
+		} else {
+			this.$watch('available', this.requestRender);
+		}
+	},
+
+	beforeDestroy() {
+		this.reset();
+	},
+
+	methods: {
+		reset() {
+			this.captcha?.reset();
+		},
+		requestRender() {
+			if (this.captcha.render && this.$refs.captcha instanceof Element) {
+				this.captcha.render(this.$refs.captcha, {
+					sitekey: this.sitekey,
+					theme: this.$store.state.device.darkMode ? 'dark' : 'light',
+					callback: this.callback,
+					'expired-callback': this.callback,
+					'error-callback': this.callback,
+				});
+			} else {
+				setTimeout(this.requestRender.bind(this), 1);
+			}
+		},
+		callback(response?: string) {
+			this.$emit('input', typeof response == 'string' ? response : null);
+		},
+	},
+});
+</script>
diff --git a/src/client/components/hcaptcha.vue b/src/client/components/hcaptcha.vue
deleted file mode 100644
index 4bc03342fe..0000000000
--- a/src/client/components/hcaptcha.vue
+++ /dev/null
@@ -1,77 +0,0 @@
-<template>
-	<div ref="hCaptcha"></div>
-</template>
-
-<script lang="ts">
-import Vue from 'vue';
-
-declare global {
-	interface Window {
-		hcaptcha?: {
-			render(container: string | Node, options: {
-				readonly [_ in 'sitekey' | 'theme' | 'type' | 'size' | 'tabindex' | 'callback' | 'expired' | 'expired-callback' | 'error-callback' | 'endpoint']?: unknown;
-			}): string;
-			remove(id: string): void;
-			execute(id: string): void;
-			reset(id: string): void;
-			getResponse(id: string): string;
-		};
-	}
-}
-
-export default Vue.extend({
-	props: {
-		sitekey: {
-			type: String,
-			required: true,
-		},
-		value: {
-			type: String,
-		},
-	},
-
-	data() {
-		return {
-			available: false,
-		};
-	},
-
-	created() {
-		if (window.hcaptcha) { // loaded
-			this.available = true;
-		} else {
-			(document.getElementById('hcaptcha') || document.head.appendChild(Object.assign(document.createElement('script'), {
-				async: true,
-				id: 'hcaptcha',
-				src: 'https://hcaptcha.com/1/api.js?render=explicit',
-			})))
-				.addEventListener('load', () => this.available = true);
-		}
-	},
-
-	mounted() {
-		if (this.available) {
-			this.render();
-		} else {
-			this.$watch('available', this.render);
-		}
-	},
-
-	methods: {
-		render() {
-			if (this.$refs.hCaptcha instanceof Element) {
-				window.hcaptcha!.render(this.$refs.hCaptcha, {
-					sitekey: this.sitekey,
-					theme: this.$store.state.device.darkMode ? 'dark' : 'light',
-					callback: this.callback,
-					'expired-callback': this.callback,
-					'error-callback': this.callback,
-				});
-			}
-		},
-		callback(response?: string) {
-			this.$emit('input', typeof response == 'string' ? response : null);
-		},
-	},
-});
-</script>
diff --git a/src/client/components/signup-dialog.vue b/src/client/components/signup-dialog.vue
index 10cdf3a567..4db79af512 100644
--- a/src/client/components/signup-dialog.vue
+++ b/src/client/components/signup-dialog.vue
@@ -1,5 +1,5 @@
 <template>
-<x-window ref="window" @closed="() => { $emit('closed'); destroyDom(); }">
+<x-window ref="window" :width="366" :height="506" @closed="() => { $emit('closed'); destroyDom(); }">
 	<template #header>{{ $t('signup') }}</template>
 	<x-signup :auto-set="autoSet" @signup="onSignup"/>
 </x-window>
diff --git a/src/client/components/signup.vue b/src/client/components/signup.vue
index 5d16a82bac..7e8bac7760 100644
--- a/src/client/components/signup.vue
+++ b/src/client/components/signup.vue
@@ -41,8 +41,8 @@
 				<a :href="meta.tosUrl" class="_link" target="_blank">{{ $t('tos') }}</a>
 			</i18n>
 		</mk-switch>
-		<div v-if="meta.enableRecaptcha" class="g-recaptcha" :data-sitekey="meta.recaptchaSiteKey" style="margin: 16px 0;"></div>
-		<h-captcha v-if="meta.enableHcaptcha" v-model="hCaptchaResponse" :sitekey="meta.hcaptchaSiteKey"/>
+		<captcha v-if="meta.enableHcaptcha" class="captcha" provider="hcaptcha" ref="hcaptcha" v-model="hCaptchaResponse" :sitekey="meta.hcaptchaSiteKey"/>
+		<captcha v-if="meta.enableRecaptcha" class="captcha" provider="grecaptcha" ref="recaptcha" v-model="reCaptchaResponse" :sitekey="meta.recaptchaSiteKey"/>
 		<mk-button type="submit" :disabled="shouldDisableSubmitting" primary>{{ $t('start') }}</mk-button>
 	</template>
 </form>
@@ -66,7 +66,7 @@ export default Vue.extend({
 		MkButton,
 		MkInput,
 		MkSwitch,
-		hCaptcha: () => import('./hcaptcha.vue').then(x => x.default),
+		captcha: () => import('./captcha.vue').then(x => x.default),
 	},
 
 	data() {
@@ -83,6 +83,7 @@ export default Vue.extend({
 			submitting: false,
 			ToSAgreement: false,
 			hCaptchaResponse: null,
+			reCaptchaResponse: null,
 			faLock, faExclamationTriangle, faSpinner, faCheck, faKey
 		}
 	},
@@ -124,14 +125,6 @@ export default Vue.extend({
 		}
 	},
 
-	mounted() {
-		if (this.meta.enableRecaptcha) {
-			const script = document.createElement('script');
-			script.setAttribute('src', 'https://www.google.com/recaptcha/api.js');
-			document.head.appendChild(script);
-		}
-	},
-
 	methods: {
 		onChangeUsername() {
 			if (this.username == '') {
@@ -189,7 +182,7 @@ export default Vue.extend({
 				password: this.password,
 				invitationCode: this.invitationCode,
 				'hcaptcha-response': this.hCaptchaResponse,
-				'g-recaptcha-response': this.meta.enableRecaptcha ? (window as any).grecaptcha.getResponse() : null
+				'g-recaptcha-response': this.meta.reCaptchaResponse,
 			}).then(() => {
 				this.$root.api('signin', {
 					username: this.username,
@@ -199,17 +192,25 @@ export default Vue.extend({
 				});
 			}).catch(() => {
 				this.submitting = false;
+				this.$refs.hcaptcha?.reset?.();
+				this.$refs.recaptcha?.reset?.();
 
 				this.$root.dialog({
 					type: 'error',
 					text: this.$t('error')
 				});
-
-				if (this.meta.enableRecaptcha) {
-					(window as any).grecaptcha.reset();
-				}
 			});
 		}
 	}
 });
 </script>
+
+<style lang="scss" scoped>
+.mk-signup {
+	padding: 32px 0 0;
+
+	.captcha {
+		margin: 16px 0;
+	}
+}
+</style>
diff --git a/src/client/pages/instance/settings.vue b/src/client/pages/instance/settings.vue
index 008d6ef1ab..f0fa846999 100644
--- a/src/client/pages/instance/settings.vue
+++ b/src/client/pages/instance/settings.vue
@@ -41,15 +41,15 @@
 	<section class="_card">
 		<div class="_title"><fa :icon="faShieldAlt"/> {{ $t('hcaptcha') }}</div>
 		<div class="_content">
-			<mk-switch v-model="enableHcaptcha">{{ $t('enableHcaptcha') }}</mk-switch>
+			<mk-switch v-model="enableHcaptcha" @input="guide('enableHcaptcha')">{{ $t('enableHcaptcha') }}</mk-switch>
 			<template v-if="enableHcaptcha">
 				<mk-input v-model="hcaptchaSiteKey" :disabled="!enableHcaptcha"><template #icon><fa :icon="faKey"/></template>{{ $t('hcaptchaSiteKey') }}</mk-input>
 				<mk-input v-model="hcaptchaSecretKey" :disabled="!enableHcaptcha"><template #icon><fa :icon="faKey"/></template>{{ $t('hcaptchaSecretKey') }}</mk-input>
 			</template>
 		</div>
-		<div class="_content" v-if="enableHcaptcha && hcaptchaSiteKey">
+		<div class="_content" v-if="enableHcaptcha">
 			<header>{{ $t('preview') }}</header>
-			<h-captcha v-if="enableHcaptcha" :sitekey="hcaptchaSiteKey"/>
+			<captcha v-if="enableHcaptcha" provider="hcaptcha" :sitekey="hcaptchaSiteKey || '10000000-ffff-ffff-ffff-000000000001'"/>
 		</div>
 		<div class="_footer">
 			<mk-button primary @click="save(true)"><fa :icon="faSave"/> {{ $t('save') }}</mk-button>
@@ -59,7 +59,7 @@
 	<section class="_card">
 		<div class="_title"><fa :icon="faShieldAlt"/> {{ $t('recaptcha') }}</div>
 		<div class="_content">
-			<mk-switch v-model="enableRecaptcha">{{ $t('enableRecaptcha') }}</mk-switch>
+			<mk-switch v-model="enableRecaptcha" @input="guide('enableRecaptcha')">{{ $t('enableRecaptcha') }}</mk-switch>
 			<template v-if="enableRecaptcha">
 				<mk-input v-model="recaptchaSiteKey" :disabled="!enableRecaptcha"><template #icon><fa :icon="faKey"/></template>{{ $t('recaptchaSiteKey') }}</mk-input>
 				<mk-input v-model="recaptchaSecretKey" :disabled="!enableRecaptcha"><template #icon><fa :icon="faKey"/></template>{{ $t('recaptchaSecretKey') }}</mk-input>
@@ -67,7 +67,7 @@
 		</div>
 		<div class="_content" v-if="enableRecaptcha && recaptchaSiteKey">
 			<header>{{ $t('preview') }}</header>
-			<div ref="recaptcha" style="margin: 16px 0 0 0;" :key="recaptchaSiteKey"></div>
+			<captcha v-if="enableRecaptcha" provider="grecaptcha" :sitekey="recaptchaSiteKey"/>
 		</div>
 		<div class="_footer">
 			<mk-button primary @click="save(true)"><fa :icon="faSave"/> {{ $t('save') }}</mk-button>
@@ -213,12 +213,6 @@ import { url } from '../../config';
 import i18n from '../../i18n';
 import getAcct from '../../../misc/acct/render';
 
-declare global {
-	interface Window {
-		onRecaptchaLoad?: Function;
-	}
-}
-
 export default Vue.extend({
 	i18n,
 
@@ -234,12 +228,11 @@ export default Vue.extend({
 		MkTextarea,
 		MkSwitch,
 		MkInfo,
-		hCaptcha: () => import('../../components/hcaptcha.vue').then(x => x.default),
+		Captcha: () => import('../../components/captcha.vue').then(x => x.default),
 	},
 
 	data() {
 		return {
-			loaded: false,
 			url,
 			proxyAccount: null,
 			proxyAccountId: null,
@@ -299,41 +292,6 @@ export default Vue.extend({
 		},
 	},
 
-	watch: {
-		enableHcaptcha(enabled) {
-			if (enabled && this.loaded && this.enableRecaptcha) {
-				this.$root.dialog({
-					type: 'question', // warning だと間違って cancel するかもしれない
-					showCancelButton: true,
-					title: this.$t('settingGuide'),
-					text: this.$t('avoidMultiCaptchaConfirm'),
-				}).then(({ canceled }) => {
-					if (canceled) {
-						return;
-					}
-
-					this.enableRecaptcha = false;
-				});
-			}
-		},
-		enableRecaptcha(enabled) {
-			if (enabled && this.loaded && this.enableHcaptcha) {
-				this.$root.dialog({
-					type: 'question', // warning だと間違って cancel するかもしれない
-					showCancelButton: true,
-					title: this.$t('settingGuide'),
-					text: this.$t('avoidMultiCaptchaConfirm'),
-				}).then(({ canceled }) => {
-					if (canceled) {
-						return;
-					}
-
-					this.enableHcaptcha = false;
-				});
-			}
-		}
-	},
-
 	created() {
 		this.name = this.meta.name;
 		this.description = this.meta.description;
@@ -388,43 +346,46 @@ export default Vue.extend({
 				this.proxyAccount = proxyAccount;
 			});
 		}
-
-		this.loaded = true;
-	},
-
-	mounted() {
-		const renderRecaptchaPreview = () => {
-			if (!(window as any).grecaptcha) return;
-			if (!this.$refs.recaptcha) return;
-			if (!this.enableRecaptcha) return;
-			if (!this.recaptchaSiteKey) return;
-			(window as any).grecaptcha.render(this.$refs.recaptcha, {
-				sitekey: this.recaptchaSiteKey
-			});
-		};
-		let recaptchaLoaded: boolean = false;
-		const requestRenderRecaptchaPreview = () => {
-			if (window.onRecaptchaLoad) { // loading
-				return;
-			}
-
-			if (recaptchaLoaded) { // loaded
-				renderRecaptchaPreview();
-			} else { // init
-				window.onRecaptchaLoad = () => {
-					recaptchaLoaded = delete window.onRecaptchaLoad;
-					renderRecaptchaPreview();
-				};
-				const script = document.createElement('script');
-				script.setAttribute('src', 'https://www.google.com/recaptcha/api.js?onload=onRecaptchaLoad');
-				document.head.appendChild(script);
-			}
-		};
-		this.$watch('enableRecaptcha', requestRenderRecaptchaPreview);
-		this.$watch('recaptchaSiteKey', requestRenderRecaptchaPreview);
 	},
 
 	methods: {
+		guide(key: 'enableHcaptcha' | 'enableRecaptcha') {
+			({
+				enableHcaptcha() {
+					if (this.enableHcaptcha && this.enableRecaptcha) {
+						this.$root.dialog({
+							type: 'question', // warning だと間違って cancel するかもしれない
+							showCancelButton: true,
+							title: this.$t('settingGuide'),
+							text: this.$t('avoidMultiCaptchaConfirm'),
+						}).then(({ canceled }) => {
+							if (canceled) {
+								return;
+							}
+
+							this.enableRecaptcha = false;
+						});
+					}
+				},
+				enableRecaptcha() {
+					if (this.enableRecaptcha && this.enableHcaptcha) {
+						this.$root.dialog({
+							type: 'question', // warning だと間違って cancel するかもしれない
+							showCancelButton: true,
+							title: this.$t('settingGuide'),
+							text: this.$t('avoidMultiCaptchaConfirm'),
+						}).then(({ canceled }) => {
+							if (canceled) {
+								return;
+							}
+
+							this.enableHcaptcha = false;
+						});
+					}
+				},
+			})[key]();
+		},
+
 		invite() {
 			this.$root.api('admin/invite').then(x => {
 				this.$root.dialog({