An voice synthesizing unit performs voice synthesizing processing, based on the state of emotion of a robot at an emotion/instinct model unit. For example, in the event that the emotion state of the robot represents "not angry", synthesized sound of "What is it?" is generated at the voice synthesizing unit. On the other hand, in the event that the emotion state of the robot represents "angry", synthesized sound of "Yeah, what?" is generated at the voice synthesizing unit, to express the anger. Thus, a robot with a high entertainment nature is provided.