We are developing a control system for a mechanical pet, AIBO, in which AIBO moves in a way that makes the user feel most comfortable as judged by his/her alpha waves. We constructed a real-time control system for customizing AIBO motion according to the user's measured alpha waves. In this paper, the results of the evaluation experiment of various new motions of AIBO for the constructed system were described. From the results, the tendencies of preferable motions of AIBO were clarified, which is useful for improvement of the system.