To pump up seawater to a water reservoir on a mountain by a wave force, to generate electric power by hydraulic power thereof, and to use the wave force to the maximum by a structure simplified to the limit.

Waves are collected and heightened by a sector type breakwater. Pressure of the wave is caught from an upper side. Seawater is pressed by the pressure of the wave to be pumped up. The seawater is held by a valve when the wave goes out. The electric power is generated by the hydraulic power from the water reservoir on the mountain.