To enable a giant swing to be continued by a simple structure in such a manner that the control of the moment of inertia is made possible in order to enable the rotation of a robot which performs the giant swing on a horizontal bar to be continued.

As a power source for the motion of the robot, a battery is built in the robot, and a receiver and a servo motor are built in the robot as well. As a control signal, a radio from an external transmitter is used. When the robot rises by the giant swing, the rotating radius is made smaller, and therefore, the arms and the legs of the robot are simultaneously bent by the servo motor, and the moment of inertia is made smaller to enable the giant swing to be continued.