diff --git a/.eslintrc.js b/.eslintrc.js
index ec5739754..acce3a24c 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -6,6 +6,7 @@ module.exports = defineConfig({
     'eslint:recommended',
     'plugin:node/recommended',
     'plugin:@typescript-eslint/recommended',
+    'prettier',
   ],
   parser: '@typescript-eslint/parser',
   parserOptions: {
@@ -31,22 +32,18 @@ module.exports = defineConfig({
         destructuring: 'all',
       },
     ],
-    '@typescript-eslint/ban-types': ['error', {
-      types: {
-        'Function': false,
-      }
-    }],
+    '@typescript-eslint/ban-types': [
+      'error',
+      {
+        types: {
+          Function: false,
+        },
+      },
+    ],
     'node/no-missing-import': [
       'error',
       {
-        allowModules: [
-          'types',
-          'estree',
-          'testUtils',
-          'less',
-          'sass',
-          'stylus',
-        ],
+        allowModules: ['types', 'estree', 'testUtils', 'less', 'sass', 'stylus'],
         tryExtensions: ['.ts', '.js', '.jsx', '.tsx', '.d.ts'],
       },
     ],
@@ -61,16 +58,10 @@ module.exports = defineConfig({
     'node/no-unpublished-require': 'off',
     'node/no-unsupported-features/es-syntax': 'off',
 
-    '@typescript-eslint/no-empty-function': [
-      'error',
-      { allow: ['arrowFunctions'] },
-    ],
+    '@typescript-eslint/no-empty-function': ['error', { allow: ['arrowFunctions'] }],
     '@typescript-eslint/no-empty-interface': 'off',
     '@typescript-eslint/no-inferrable-types': 'off',
     '@typescript-eslint/no-var-requires': 'off',
-    '@typescript-eslint/consistent-type-imports': [
-      'error',
-      { prefer: 'type-imports' },
-    ],
+    '@typescript-eslint/consistent-type-imports': ['error', { prefer: 'type-imports' }],
   },
 })
diff --git a/.prettierrc b/.prettierrc
new file mode 100644
index 000000000..a456dc9af
--- /dev/null
+++ b/.prettierrc
@@ -0,0 +1,9 @@
+{
+  "printWidth": 100,
+  "trailingComma": "es5",
+  "tabWidth": 2,
+  "semi": false,
+  "singleQuote": true,
+  "jsxSingleQuote": true,
+  "endOfLine": "lf"
+}
diff --git a/package.json b/package.json
index ac5b2c552..833793e81 100644
--- a/package.json
+++ b/package.json
@@ -50,7 +50,7 @@
   },
   "scripts": {
     "test": "jest",
-    "lint": "eslint --ext js,ts src .eslintrc.js test",
+    "lint": "eslint --ext js,ts src .eslintrc.js test && prettier --check src",
     "build": "rimraf dist && tsc",
     "watch": "tsc -w",
     "prepublishOnly": "yarn build"
@@ -82,18 +82,18 @@
     "@typescript-eslint/eslint-plugin": "^5.9.0",
     "@typescript-eslint/parser": "^5.9.0",
     "eslint": "^7.26.0",
-    "eslint-config-prettier": "^8.1.0",
+    "eslint-config-prettier": "^8.3.0",
     "eslint-define-config": "^1.2.1",
     "eslint-import-resolver-typescript": "^2.0.0",
     "eslint-plugin-eslint-comments": "^3.2.0",
     "eslint-plugin-flowtype": "^5.7.2",
     "eslint-plugin-import": "^2.20.2",
     "eslint-plugin-node": "^11.1.0",
-    "eslint-plugin-prettier": "^4.0.0",
     "form-data": "^4.0.0",
     "jest": "^27.4.5",
     "jest-environment-miniflare": "^2.0.0",
     "mustache": "^4.2.0",
+    "prettier": "^2.5.1",
     "rimraf": "^3.0.2",
     "ts-jest": "^27.1.2",
     "typescript": "^4.5.5"
diff --git a/src/middleware/cors/cors.test.ts b/src/middleware/cors/cors.test.ts
index da52b569f..ae6e52dff 100644
--- a/src/middleware/cors/cors.test.ts
+++ b/src/middleware/cors/cors.test.ts
@@ -39,7 +39,10 @@ describe('CORS by Middleware', () => {
 
     expect(res.status).toBe(204)
     expect(res.headers.get('Access-Control-Allow-Methods').split(',')[0]).toBe('GET')
-    expect(res.headers.get('Access-Control-Allow-Headers').split(',')).toEqual(['X-PINGOTHER', 'Content-Type'])
+    expect(res.headers.get('Access-Control-Allow-Headers').split(',')).toEqual([
+      'X-PINGOTHER',
+      'Content-Type',
+    ])
   })
 
   it('Preflight with options', async () => {
@@ -52,7 +55,11 @@ describe('CORS by Middleware', () => {
       'X-Custom-Header',
       'Upgrade-Insecure-Requests',
     ])
-    expect(res.headers.get('Access-Control-Allow-Methods').split(/\s*,\s*/)).toEqual(['POST', 'GET', 'OPTIONS'])
+    expect(res.headers.get('Access-Control-Allow-Methods').split(/\s*,\s*/)).toEqual([
+      'POST',
+      'GET',
+      'OPTIONS',
+    ])
     expect(res.headers.get('Access-Control-Expose-Headers').split(/\s*,\s*/)).toEqual([
       'Content-Length',
       'X-Kuma-Revision',
diff --git a/src/middleware/logger/logger.ts b/src/middleware/logger/logger.ts
index beeef4ed2..164ec7b70 100644
--- a/src/middleware/logger/logger.ts
+++ b/src/middleware/logger/logger.ts
@@ -1,10 +1,7 @@
 import { getPathFromURL } from '../../utils/url'
 import type { Context } from '../../context'
 
-const humanize = (
-  n: string[],
-  opts?: { delimiter?: string; separator?: string }
-) => {
+const humanize = (n: string[], opts?: { delimiter?: string; separator?: string }) => {
   const options = opts || {}
   const d = options.delimiter || ','
   const s = options.separator || '.'
@@ -15,9 +12,7 @@ const humanize = (
 
 const time = (start: number) => {
   const delta = Date.now() - start
-  return humanize([
-    delta < 10000 ? delta + 'ms' : Math.round(delta / 1000) + 's',
-  ])
+  return humanize([delta < 10000 ? delta + 'ms' : Math.round(delta / 1000) + 's'])
 }
 
 const LogPrefix = {
@@ -38,7 +33,7 @@ const colorStatus = (status: number = 0) => {
   }
   return out[(status / 100) | 0]
 }
-type PrintFunc = (str: string, ...rest: string[]) => void;
+type PrintFunc = (str: string, ...rest: string[]) => void
 
 function log(
   fn: PrintFunc,
@@ -52,9 +47,7 @@ function log(
   const out =
     prefix === LogPrefix.Incoming
       ? `  ${prefix} ${method} ${path}`
-      : `  ${prefix} ${method} ${path} ${colorStatus(
-          status
-        )} ${elasped} ${contentLength}`
+      : `  ${prefix} ${method} ${path} ${colorStatus(status)} ${elasped} ${contentLength}`
   fn(out)
 }
 
@@ -75,20 +68,8 @@ export const logger = (fn = console.log) => {
     }
 
     const len = parseFloat(c.res.headers.get('Content-Length'))
-    const contentLength = isNaN(len)
-      ? '0'
-      : len < 1024
-      ? `${len}b`
-      : `${len / 1024}kB`
+    const contentLength = isNaN(len) ? '0' : len < 1024 ? `${len}b` : `${len / 1024}kB`
 
-    log(
-      fn,
-      LogPrefix.Outgoing,
-      method,
-      path,
-      c.res.status,
-      time(start),
-      contentLength
-    )
+    log(fn, LogPrefix.Outgoing, method, path, c.res.status, time(start), contentLength)
   }
 }
diff --git a/src/middleware/serve-static/serve-static.ts b/src/middleware/serve-static/serve-static.ts
index c18c3787b..927a685d4 100644
--- a/src/middleware/serve-static/serve-static.ts
+++ b/src/middleware/serve-static/serve-static.ts
@@ -14,7 +14,11 @@ export const serveStatic = (opt: Options = { root: '' }) => {
     await next()
     const url = new URL(c.req.url)
 
-    const path = getKVFilePath({ filename: url.pathname, root: opt.root, defaultDocument: DEFAULT_DOCUMENT })
+    const path = getKVFilePath({
+      filename: url.pathname,
+      root: opt.root,
+      defaultDocument: DEFAULT_DOCUMENT,
+    })
 
     const content = await getContentFromKVAsset(path)
     if (content) {
diff --git a/src/utils/buffer.test.ts b/src/utils/buffer.test.ts
index b1829d493..82a2203be 100644
--- a/src/utils/buffer.test.ts
+++ b/src/utils/buffer.test.ts
@@ -17,8 +17,12 @@ describe('buffer', () => {
   })
 
   it('sha256', async () => {
-    expect(await sha256('hono')).toBe('8b3dc17add91b7e8f0b5109a389927d66001139cd9b03fa7b95f83126e1b2b23')
-    expect(await sha256('炎')).toBe('1fddc5a562ee1fbeb4fc6def7d4be4911fcdae4273b02ae3a507b170ba0ea169')
+    expect(await sha256('hono')).toBe(
+      '8b3dc17add91b7e8f0b5109a389927d66001139cd9b03fa7b95f83126e1b2b23'
+    )
+    expect(await sha256('炎')).toBe(
+      '1fddc5a562ee1fbeb4fc6def7d4be4911fcdae4273b02ae3a507b170ba0ea169'
+    )
 
     expect(await sha256('abcdedf')).not.toBe('abcdef')
   })
@@ -39,8 +43,12 @@ describe('buffer', () => {
 
   it('negative', async () => {
     expect(await timingSafeEqual('a', 'b')).toBe(false)
-    expect(await timingSafeEqual('a', 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa')).toBe(false)
-    expect(await timingSafeEqual('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa', 'a')).toBe(false)
+    expect(
+      await timingSafeEqual('a', 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa')
+    ).toBe(false)
+    expect(
+      await timingSafeEqual('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa', 'a')
+    ).toBe(false)
     expect(await timingSafeEqual('alpha', 'beta')).toBe(false)
     expect(await timingSafeEqual(false, true)).toBe(false)
     expect(await timingSafeEqual(false, undefined)).toBe(false)
diff --git a/src/utils/buffer.ts b/src/utils/buffer.ts
index 09af06925..96a10723e 100644
--- a/src/utils/buffer.ts
+++ b/src/utils/buffer.ts
@@ -48,7 +48,9 @@ export const sha256 = async (a: string | object | boolean): Promise<string> => {
       },
       new TextEncoder().encode(String(a))
     )
-    const hash = Array.prototype.map.call(new Uint8Array(buffer), (x) => ('00' + x.toString(16)).slice(-2)).join('')
+    const hash = Array.prototype.map
+      .call(new Uint8Array(buffer), (x) => ('00' + x.toString(16)).slice(-2))
+      .join('')
     return hash
   }
 
@@ -62,7 +64,10 @@ export const sha256 = async (a: string | object | boolean): Promise<string> => {
   }
 }
 
-export const timingSafeEqual = async (a: string | object | boolean, b: string | object | boolean) => {
+export const timingSafeEqual = async (
+  a: string | object | boolean,
+  b: string | object | boolean
+) => {
   const sa = await sha256(a)
   const sb = await sha256(b)
   return sa === sb && a === b
diff --git a/src/utils/cloudflare.test.ts b/src/utils/cloudflare.test.ts
index a3e8ba869..25260e3d8 100644
--- a/src/utils/cloudflare.test.ts
+++ b/src/utils/cloudflare.test.ts
@@ -39,7 +39,9 @@ describe('Utils for Cloudflare Workers', () => {
     expect(getKVFilePath({ filename: 'foo.txt', root: 'bar' })).toBe('bar/foo.txt')
 
     expect(getKVFilePath({ filename: 'foo', defaultDocument: 'index.txt' })).toBe('foo/index.txt')
-    expect(getKVFilePath({ filename: 'foo', root: 'bar', defaultDocument: 'index.txt' })).toBe('bar/foo/index.txt')
+    expect(getKVFilePath({ filename: 'foo', root: 'bar', defaultDocument: 'index.txt' })).toBe(
+      'bar/foo/index.txt'
+    )
 
     expect(getKVFilePath({ filename: './foo' })).toBe('foo/index.html')
     expect(getKVFilePath({ filename: 'foo', root: './bar' })).toBe('bar/foo/index.html')
diff --git a/yarn.lock b/yarn.lock
index ea580fc09..7b27dbc16 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1517,7 +1517,7 @@ escodegen@^2.0.0:
   optionalDependencies:
     source-map "~0.6.1"
 
-eslint-config-prettier@^8.1.0:
+eslint-config-prettier@^8.3.0:
   version "8.3.0"
   resolved "https://registry.yarnpkg.com/eslint-config-prettier/-/eslint-config-prettier-8.3.0.tgz#f7471b20b6fe8a9a9254cc684454202886a2dd7a"
   integrity sha512-BgZuLUSeKzvlL/VUjx/Yb787VQ26RU3gGjA3iiFvdsp/2bMfVIWUVP7tjxtjS0e+HP409cPlPvNkQloz8C91ew==
@@ -1609,13 +1609,6 @@ eslint-plugin-node@^11.1.0:
     resolve "^1.10.1"
     semver "^6.1.0"
 
-eslint-plugin-prettier@^4.0.0:
-  version "4.0.0"
-  resolved "https://registry.yarnpkg.com/eslint-plugin-prettier/-/eslint-plugin-prettier-4.0.0.tgz#8b99d1e4b8b24a762472b4567992023619cb98e0"
-  integrity sha512-98MqmCJ7vJodoQK359bqQWaxOE0CS8paAz/GgjaZLyex4TTk3g9HugoO89EqWCrFiOqn9EVvcoo7gZzONCWVwQ==
-  dependencies:
-    prettier-linter-helpers "^1.0.0"
-
 eslint-scope@^5.1.1:
   version "5.1.1"
   resolved "https://registry.yarnpkg.com/eslint-scope/-/eslint-scope-5.1.1.tgz#e786e59a66cb92b3f6c1fb0d508aab174848f48c"
@@ -1777,11 +1770,6 @@ fast-deep-equal@^3.1.1, fast-deep-equal@^3.1.3:
   resolved "https://registry.yarnpkg.com/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz#3a7d56b559d6cbc3eb512325244e619a65c6c525"
   integrity sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q==
 
-fast-diff@^1.1.2:
-  version "1.2.0"
-  resolved "https://registry.yarnpkg.com/fast-diff/-/fast-diff-1.2.0.tgz#73ee11982d86caaf7959828d519cfe927fac5f03"
-  integrity sha512-xJuoT5+L99XlZ8twedaRf6Ax2TgQVxvgZOYoPKqZufmJib0tL2tegPBOZb1pVNgIhlqDlA0eO0c3wBvQcmzx4w==
-
 fast-glob@^3.2.9:
   version "3.2.11"
   resolved "https://registry.yarnpkg.com/fast-glob/-/fast-glob-3.2.11.tgz#a1172ad95ceb8a16e20caa5c5e56480e5129c1d9"
@@ -3189,12 +3177,10 @@ prelude-ls@~1.1.2:
   resolved "https://registry.yarnpkg.com/prelude-ls/-/prelude-ls-1.1.2.tgz#21932a549f5e52ffd9a827f570e04be62a97da54"
   integrity sha1-IZMqVJ9eUv/ZqCf1cOBL5iqX2lQ=
 
-prettier-linter-helpers@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/prettier-linter-helpers/-/prettier-linter-helpers-1.0.0.tgz#d23d41fe1375646de2d0104d3454a3008802cf7b"
-  integrity sha512-GbK2cP9nraSSUF9N2XwUwqfzlAFlMNYYl+ShE/V+H8a9uNl/oUqB1w2EL54Jh0OlyRSd8RfWYJ3coVS4TROP2w==
-  dependencies:
-    fast-diff "^1.1.2"
+prettier@^2.5.1:
+  version "2.5.1"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-2.5.1.tgz#fff75fa9d519c54cf0fce328c1017d94546bc56a"
+  integrity sha512-vBZcPRUR5MZJwoyi3ZoyQlc1rXeEck8KgeC9AwwOn+exuxLxq5toTRDTSaVrXHxelDMHy9zlicw8u66yxoSUFg==
 
 pretty-format@^27.0.0, pretty-format@^27.4.6:
   version "27.4.6"