Familiarity is one of the most important requirements for human symbiosis robots such as care service robot. Many studies have been made to provide robots with the familiarity by improving their appearance, facial expression and smoothness of the movement. This paper presents a new concept, called a “robot avatar.”A robot avatar is a small robot mounted on a main robot and equipped with minimum function to play some gestures according to every scene of the task execution of the main robot. By looking at the avatar, a user feels as if the avatar is controlling the main robot. Therefore a user is informed of the next behavior of the main robot by the avatar. A prototype of the avatar named CHIRIS is designed and installed to an intelligent service robot IRIS developed by the authors. IRIS can execute some simple tasks such as serving beverages by verbal request of the user. Utilizing CHIRIS, some psychological tests about the impression of IRIS during its task execution were carried out using video. Test results showed that CHIRIS is effective to give more familiar impression to the users.