NOVELTY - The apparatus has a wave receiver tank (1) in which sealed space is formed when the tank is installed in an oceanfront underwater (U) so that an incoming wave is received and a wave receptacle (2) is shut. A wave receiving plate (3) s provided to bring incoming wave together in wave receptacle of wave receiver tank. A generator (7) is provided to receive and generate electric-power from the pressure of the air in the wave receiver tank that is pushed on the seawater which enters from the wave receptacle and rises by the sealed space, and is compressed.    USE - Apparatus for generating electric power using energy of incoming wave.    ADVANTAGE - The generator is provided to receive and generate electric-power from the pressure of the air in the wave receiver tank that is pushed on the seawater which enters from the wave receptacle and rises by the sealed space, and is compressed so that elevation difference is produced with big water level of seawater in upper space of tank so as to largely compress the air in upper space of tank. Thus, the electric power generation amount is increased efficiently corresponding to the height change of peak portion and highly automatically heaping up seawater in upper space of tank. The laterally long blade of the portion maintains the state of receiving the pressure of seawater from inner side and is closed when the laterally long blade receives the pressure of the air from inner side, and is closed to make the seawater to heap up largely so as to prevent the leakage of compressed air obtained by the rise of seawater from a laterally long blade portion to the exterior of wave receiver tank, and to reduce the pressure of air in upper space of tank. Thus, the leakage of air in upper space of tank is prevented effectively without the kinetic energy of incoming wave even when the water level of peak portion of wave changes a lot up and down.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of the up-and-down opening and closing plate.    Wave receiver tank (1)    Wave receptacle (2)    Wave receiving plate (3)    Generator (7)    Oceanfront underwater (U)