A gyro wave-activated power generator utilizing wave energy which has, as a component, a control moment gyro, and which comprises a floating body (1), a control moment gyro (5) supported by the floating body, and a power generator (10) connected to the gimbal shaft of the gyro through a gearing to increase speed(9), and is characterized by the gimbal (6) of the gyro being rotated by the movement of the floating body by wave energy to drive the power generator (10) for power generation.