Abstract. In intercultural communication, there are large barriers when the languages and the cultures are different. It is undoubtedly preferable for people to have smooth communications using their mother language. Therefore, we have developed a chat system called AnnoChat. AnnoChat has an annotation function for smooth intercultural communications. We applied AnnoChat in experiments with Japanese, Chinese, and Korean speakers. The results of the experiments showed that about 70% of the added annotations were reusable as intercultural knowledge information. About 20% of the added annotations were used to supplement information that could not be described while chatting. It is thought to be an effective example of applying annotation in intercultural communications.