diff --git a/rag/cdk/lambda/handler.ts b/rag/cdk/lambda/handler.ts
index 73217842..4a22fb86 100644
--- a/rag/cdk/lambda/handler.ts
+++ b/rag/cdk/lambda/handler.ts
@@ -32,9 +32,6 @@ export async function handle(
       'あなたは文書からコンテキストを取得する専門家です。ツールを使用してユーザーの質問に答える手助けをしてください。必ずユーザーの質問と同じ言語で答えてください。';
 
     const { platform, model, modelName } = selectLlm(modelType);
-
-    const agent = createAgent({ model, tools: [tool], systemPrompt });
-
     // Initialize Langfuse callback handler
     const langfuseHandler = langfuse.publicKey && langfuse.secretKey ? new CallbackHandler({
       sessionId,
@@ -43,6 +40,12 @@ export async function handle(
       tags: [modelName],
     }) : undefined;
 
+    const agent = createAgent({
+      model,
+      tools: [tool],
+      systemPrompt,
+    });
+
     logger.debug(`Langfuse: ${langfuseHandler ? 'enable' : 'disable'}`);
 
     const threadId = uuidv7();
@@ -54,8 +57,9 @@ export async function handle(
         configurable: {
           sessionId,
           thread_id: threadId,
-          callbacks: langfuseHandler ? [langfuseHandler] : [],
         },
+        //@ts-expect-error LangChain.js の型定義誤り？
+        callbacks: langfuseHandler ? [langfuseHandler] : [],
       },
     );
     for await (const sEvent of stream) {