diff --git a/src/ts/process/stringlize.ts b/src/ts/process/stringlize.ts
index 6b762fa2..641e3b11 100644
--- a/src/ts/process/stringlize.ts
+++ b/src/ts/process/stringlize.ts
@@ -57,7 +57,7 @@ export function unstringlizeChat(text:string, formated:OpenAIChat[], char:string
 export function stringlizeAINChat(formated:OpenAIChat[], char:string = ''){
     let resultString:string[] = []
     for(const form of formated){
-        if(form.memo.startsWith("newChat")){
+        if(form.memo && form.memo.startsWith("newChat")){
             resultString.push("[新しいチャットの始まり]")
             continue
         }