A robot apparatus in which the storage capacity necessary for holding motion data is diminished in representing the emotion by motions exploiting the body resources. In demonstrating component behaviors of the robot apparatus, the basic posture, as the posture at the start time of one or plural movements forming a component behavior, is changed to express the emotion. Specifically, the robot apparatus includes variations for expressing the emotion for the basic posture (basic posture for the emotion). The respective resources are actuated from the basic posture for the emotion and reversion is made again to the basic posture to demonstrate the emotion.