diff --git a/package-lock.json b/package-lock.json
index 73eeae0..4974fa3 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -18,6 +18,7 @@
       },
       "devDependencies": {
         "@types/minimist": "^1.2.5",
+        "@types/node": "^22.3.0",
         "eslint": "^9.9.0",
         "eslint-config-flat-gitignore": "^0.1.8",
         "eslint-config-prettier": "^9.1.0",
@@ -898,7 +899,6 @@
       "version": "22.3.0",
       "resolved": "https://registry.npmjs.org/@types/node/-/node-22.3.0.tgz",
       "integrity": "sha512-nrWpWVaDZuaVc5X84xJ0vNrLvomM205oQyLsRt7OHNZbSHslcWsvgFR7O7hire2ZonjLrWBbedmotmIlJDVd6g==",
-      "peer": true,
       "dependencies": {
         "undici-types": "~6.18.2"
       }
@@ -3041,8 +3041,7 @@
     "node_modules/undici-types": {
       "version": "6.18.2",
       "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-6.18.2.tgz",
-      "integrity": "sha512-5ruQbENj95yDYJNS3TvcaxPMshV7aizdv/hWYjGIKoANWKjhWNBsr2YEuYZKodQulB1b8l7ILOuDQep3afowQQ==",
-      "peer": true
+      "integrity": "sha512-5ruQbENj95yDYJNS3TvcaxPMshV7aizdv/hWYjGIKoANWKjhWNBsr2YEuYZKodQulB1b8l7ILOuDQep3afowQQ=="
     },
     "node_modules/uri-js": {
       "version": "4.4.1",
diff --git a/package.json b/package.json
index bb6ce90..5878abe 100644
--- a/package.json
+++ b/package.json
@@ -36,6 +36,7 @@
   },
   "devDependencies": {
     "@types/minimist": "^1.2.5",
+    "@types/node": "^22.3.0",
     "eslint": "^9.9.0",
     "eslint-config-flat-gitignore": "^0.1.8",
     "eslint-config-prettier": "^9.1.0",
diff --git a/samples/openapi.json b/samples/openapi.json
index 13aede5..12fd1d7 100644
--- a/samples/openapi.json
+++ b/samples/openapi.json
@@ -1,8 +1,8 @@
 {
   "openapi": "3.1.0",
   "info": {
-    "title": "openapi api",
-    "version": "v0.0"
+    "title": "title test api",
+    "version": "v1.1"
   },
   "paths": {
     "/api/stream/v1/stories/{storyId}": {
diff --git a/src/index.ts b/src/index.ts
index f7ec73a..5968eaf 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,7 +1,7 @@
 import type { AspidaMethodParams } from 'aspida';
 import type { DirentTree } from 'aspida/dist/cjs/getDirentTree';
 import { getDirentTree } from 'aspida/dist/cjs/getDirentTree';
-import { unlinkSync, writeFileSync } from 'fs';
+import { existsSync, readFileSync, unlinkSync, writeFileSync } from 'fs';
 import type { OpenAPIV3_1 } from 'openapi-types';
 import { join } from 'path';
 import * as TJS from 'typescript-json-schema';
@@ -42,6 +42,10 @@ type AllMethods = [${paths.map((_, i) => `Methods${i}`).join(', ')}]`;
 
     const program = TJS.getProgramFromFiles([typeFilePath], compilerOptions);
     const schema = TJS.generateSchema(program, 'AllMethods', { required: true });
+    const existingDoc: OpenAPIV3_1.Document | undefined = existsSync(config.output)
+      ? JSON.parse(readFileSync(config.output, 'utf8'))
+      : undefined;
+
     const doc: OpenAPIV3_1.Document = {
       openapi: '3.1.0',
       info: {
@@ -49,6 +53,7 @@ type AllMethods = [${paths.map((_, i) => `Methods${i}`).join(', ')}]`;
         version: 'v0.0',
       },
       servers: config.baseURL ? [{ url: config.baseURL }] : undefined,
+      ...existingDoc,
       paths: {},
       components: { schemas: schema?.definitions as any },
     };