PURPOSE: To provide a high efficiency pump by modeling two-dimensionally a flapping mechanism of small bee to apply the mechanism to a new pump.

CONSTITUTION: After two wings 1 are closed together, they are rotated about their rear edges. Then, both wings 1 have a certain angle of incidence and make translational motion to be kept away from each other. When both wings 1 reach a wall surface 2, then both wings are rotated abut the front edges until they become parallel to each other. Thereafter, both wings 1 are opened about the rear edges, made move parallelly, rotated centering the front edges at the central portion of water path, and closed together. Then, they return to the initial condition and this process is repeated.