diff --git a/src/util/jsonp.ts b/src/util/jsonp.ts
index c76b824..d67c794 100644
--- a/src/util/jsonp.ts
+++ b/src/util/jsonp.ts
@@ -75,14 +75,23 @@ export function jsonp<T>(
     
     // リソース解放用の関数を定義
     // スクリプトタグの削除、コールバック関数のクリーンアップ、タイマーのクリアを行う
-    const cleanup = function () {
+    const cleanup = function (isTimeout = false) {
       // Remove the script tag.
       if (script && script.parentNode) {
         script.parentNode.removeChild(script);
       }
 
-      // コールバック関数を空の関数に置き換えてメモリリークを防止
-      window[id] = noop;
+      if (isTimeout) {
+        // タイムアウト時は遅延レスポンスによるコンソールエラーを避けるためにnoopを代入
+        window[id] = noop;
+      } else {
+        // 成功時は完全に削除してメモリリークを防止
+        try {
+          delete window[id];
+        } catch {
+          window[id] = undefined as any;
+        }
+      }
 
       if (timer) {
         clearTimeout(timer);
@@ -94,7 +103,7 @@ export function jsonp<T>(
     const timer =
       timeout > 0
         ? setTimeout(() => {
-          cleanup();
+          cleanup(true);
           reject(new Error("Timeout"));
         }, timeout)
         : undefined;
diff --git a/test/util/jsonp.test.ts b/test/util/jsonp.test.ts
index b30ed57..46c9cbd 100644
--- a/test/util/jsonp.test.ts
+++ b/test/util/jsonp.test.ts
@@ -130,6 +130,10 @@ describe('jsonp', () => {
     const result = await jsonpPromise;
     expect(result).toEqual(mockData);
     expect(mockParentNode.insertBefore).toHaveBeenCalledWith(mockScript, expect.anything());
+
+    // Check if callback is cleaned up (deleted on success)
+    expect(window[callbackName]).toBeUndefined();
+    expect(callbackName in window).toBe(false);
   });
 
   test('should apply custom options', async () => {
@@ -161,6 +165,10 @@ describe('jsonp', () => {
 
     const result = await jsonpPromise;
     expect(result).toEqual(mockData);
+
+    // Check if callback is cleaned up (deleted on success)
+    expect(window[callbackName]).toBeUndefined();
+    expect(callbackName in window).toBe(false);
   });
 
   test('should timeout and reject the promise', async () => {
@@ -173,6 +181,12 @@ describe('jsonp', () => {
     vi.advanceTimersByTime(1001);
 
     await expect(promise).rejects.toThrow('Timeout');
+
+    // Check if callback is replaced by noop on timeout (not deleted)
+    const timeoutId = Object.keys(window).find(key => key.startsWith('__jp') && typeof window[key] === 'function');
+    expect(timeoutId).toBeDefined();
+    expect(typeof window[timeoutId!]).toBe('function');
+    expect(timeoutId! in window).toBe(true);
   });
 
   test('should use document.head if no script tags exist', async () => {