diff --git a/package.json b/package.json
index 8223383..0981960 100644
--- a/package.json
+++ b/package.json
@@ -92,7 +92,7 @@
   },
   "dependencies": {
     "@himenon/openapi-parameter-formatter": "^0.2.2",
-    "node-fetch": "2"
+    "node-fetch": "2.6.7"
   },
   "devDependencies": {
     "@commitlint/cli": "16.2.1",
@@ -100,6 +100,7 @@
     "@himenon/openapi-typescript-code-generator": "^0.16.0",
     "@types/jest": "27.4.1",
     "@types/node": "17.0.21",
+    "@types/node-fetch": "^2.6.1",
     "@types/rimraf": "3.0.2",
     "@typescript-eslint/eslint-plugin": "5.14.0",
     "@typescript-eslint/parser": "5.14.0",
diff --git a/src/ApiClientImpl.ts b/src/ApiClientImpl.ts
index 530f0a5..d79f22a 100644
--- a/src/ApiClientImpl.ts
+++ b/src/ApiClientImpl.ts
@@ -23,7 +23,13 @@ export const generateQueryString = (queryParameters: QueryParameters | undefined
   return queries.join("&");
 };
 
-export const create = (accessToken?: string): ApiClient<Types.RequestOption> => {
+export interface Params {
+  accessToken?: string;
+  fetch: Types.FetchFunction;
+}
+
+export const create = (params: Params): ApiClient<Types.RequestOption> => {
+  const { accessToken, fetch: _fetch } = params;
   const apiClientImpl: ApiClient<Types.RequestOption> = {
     request: async (httpMethod, url, headers, requestBody, queryParameters): Promise<any> => {
       const query = generateQueryString(queryParameters);
@@ -32,7 +38,7 @@ export const create = (accessToken?: string): ApiClient<Types.RequestOption> =>
         ...headers,
         Authorization: "token " + accessToken,
       };
-      const response = await fetch(requestUrl, {
+      const response = await _fetch(requestUrl, {
         body: JSON.stringify(requestBody),
         headers: requestHeaders,
         method: httpMethod,
diff --git a/src/index.ts b/src/index.ts
index 3e1582d..425db42 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,6 +1,8 @@
 import { GitHub } from "./GitHub";
 import * as ApiClientImpl from "./ApiClientImpl";
 import { Client, Schemas } from "./api";
+import { FetchFunction } from "./types";
+import nodeFetch from "node-fetch";
 export * from "./types";
 
 export { Schemas, GitHub, Client };
@@ -15,11 +17,19 @@ export interface InitializeParameter {
   baseUrl?: string | "https://api.github.com";
   /** GitHub Access Token */
   accessToken?: string;
+  /**
+   * Default: node-fetch
+   */
+  fetch?: FetchFunction;
 }
 
 export const create = (args: InitializeParameter): GitHub => {
   const baseUrl = args.baseUrl || "https://api.github.com";
-  const apiClientImpl = ApiClientImpl.create(args.accessToken);
+  const _fetch: FetchFunction = args.fetch || nodeFetch;
+  const apiClientImpl = ApiClientImpl.create({
+    accessToken: args.accessToken,
+    fetch: _fetch,
+  });
   const client = new Client(apiClientImpl, baseUrl);
   const github = new GitHub(client, args.owner, args.repo);
   return github;
diff --git a/src/types.ts b/src/types.ts
index 8fbac35..d6ce4ee 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,5 +1,9 @@
+import type { RequestInfo, RequestInit, Response } from "node-fetch";
+
 export interface RequestOption {}
 
+export type FetchFunction = (url: RequestInfo, init?: RequestInit) => Promise<Response>;
+
 export interface CreateBranchArgs {
   branchName: string;
   baseBranchName?: string;
diff --git a/yarn.lock b/yarn.lock
index f70b0e3..a86b4c1 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2078,6 +2078,14 @@
   resolved "https://registry.yarnpkg.com/@types/minimist/-/minimist-1.2.1.tgz#283f669ff76d7b8260df8ab7a4262cc83d988256"
   integrity sha512-fZQQafSREFyuZcdWFAExYjBiCL7AUCdgsk80iO0q4yihYYdcIiH28CcuPTGFgLOCC8RlW49GSQxdHwZP+I7CNg==
 
+"@types/node-fetch@^2.6.1":
+  version "2.6.1"
+  resolved "https://registry.yarnpkg.com/@types/node-fetch/-/node-fetch-2.6.1.tgz#8f127c50481db65886800ef496f20bbf15518975"
+  integrity sha512-oMqjURCaxoSIsHSr1E47QHzbmzNR5rK8McHuNb11BOM9cHcIK3Avy0s/b2JlXHoQGTYS3NsvWzV1M0iK7l0wbA==
+  dependencies:
+    "@types/node" "*"
+    form-data "^3.0.0"
+
 "@types/node@*":
   version "14.14.7"
   resolved "https://registry.yarnpkg.com/@types/node/-/node-14.14.7.tgz#8ea1e8f8eae2430cf440564b98c6dfce1ec5945d"
@@ -6406,7 +6414,7 @@ nice-try@^1.0.4:
   resolved "https://registry.yarnpkg.com/nice-try/-/nice-try-1.0.5.tgz#a3378a7696ce7d223e88fc9b764bd7ef1089e366"
   integrity sha512-1nh45deeb5olNY7eX82BkPO7SSxR5SSYJiPTrTdFUVYwAl8CKMA5N9PjTYkHiRjisVcxcQ1HXdLhx2qxxJzLNQ==
 
-node-fetch@2:
+node-fetch@2.6.7:
   version "2.6.7"
   resolved "https://registry.yarnpkg.com/node-fetch/-/node-fetch-2.6.7.tgz#24de9fba827e3b4ae44dc8b20256a379160052ad"
   integrity sha512-ZjMPFEfVx5j+y2yF35Kzx5sF7kDzxuDj6ziH4FFbOp87zKDZNx8yExJIb05OGF4Nlt9IHFIMBkRl41VdvcNdbQ==