To surely erect impeller blades at the forward movement side thereof by a rotor and, further, to surely push down these impeller blades at the backward movement side thereof by a rotor. By providing a fluid passage frame body 21 above a rotor 10 to form a fluid passage 20, rotatably disposing impeller blades 15 on rotor 10, forming a fluid receiving part 15a and a stopper part 15b shorter than this fluid receiving part into an L shape, and disposing stopper part 15b on the side of fluid receiving part 15a receiving fluid pressure from fluid passage 20 such as to maintain fluid receiving part 15a in an erected position. An impeller blade erecting passage pipe 30 is formed on rotor 10 such that the diameter of one end thereof 30a is larger than the diameter of the other end thereof 30b. An inclined plate 31 and an impeller blade downward passage pipe 32 is provided on the outlet side of fluid passage 20, this impeller blade downward passage pipe 32 formed such that one end thereof 32a on the inclined plate 31 side has a larger diameter than the other end thereof 32b on an impeller blade passage frame body 22.