To provide a valuable and convenient wave-power pump operated to suck a large amount of sea water by utilizing the ocean-wave energy of nature without depending on generally-used expensive energy sources such as electric power and oil which may contaminate the environment.

A funnel member 50 for sucking sea-water is mounted on an open-side tip part of a pump body 10, a water duct 80 and a switch 70 for introducing sea water are mounted on a close-side rear end part of the pump body 10, the switch 70 is opened in backrush, and a piston plate 40 is pushed by the sea water flowing from the funnel member 50 in incoming surf, whereby the sea water in the pump body 10 sucked in the former backrush is force-fed to the water duct 80, since the switch 70 for introducing sea water is closed. Whereby the pump is operated by ocean-wave energy, and the sea water is sucked.