PURPOSE: To simplify equipment by driving a waterwheel generator by the action of negative pressure caused by the discharge/suction water in a rotating discharge pipe by installing the waterwheel generator in the conduit introducing water into the rotationing discharge pipe.

CONSTITUTION: A rotating discharge pipe 4 is installed in a space outside a reservoir 1, making the end 5B of a horizontal pipe 4B a discharge port and the lower end 5A of a vertical pipe 4A a suction port. The rotating discharge pipe 4 is turned by the drive of a motor 11, and the hydraulic pressure in a conduit 15B becomes negative to form water current flowing from a conduit 15A to the conduit 15B, by which a waterwheel generator 20 in this water current is made to generate electricity. Thus, large generator output can be obtained by an extremely small-scale power generating equipment.