Speech of a user is recognized in a speech recognizing unit. Based on a result of the speech recognition, a language processing unit, a dialog managing unit and a response generating unit cooperatively created a dialog sentence for exchanging a dialog with the user. Also, based on the speech recognition result, the dialog managing unit collects user information regarding, e.g., interests and tastes of the user. Therefore, the user information regarding, the interests and tastes of the user can be easily collected.