To allow balls to be easily caught and operation to be performed in a game using balls since physical fraudulence common to a TV game cannot be performed in a game using a robot, steering tends to be difficult, and the difficult steering makes the robot game uninteresting, so that the steering needs to be made easy.

A ball-catch function is provided for a front part of the robot and a function for performing curve driving of a minimum radius of gyration whose gyration center is determined between a robot outer edge and a robot center is provided. In steering control of normal driving, a driving radius of gyration is set large so as to make steering easy, and a steering area of the minimum radius of gyration is set beyond the steering range of normal driving.