To provide an engine which consumes no petroleum as low-yield resources in Japan but utilizes wind/hydraulic power free from public nuisance such as exhaust gas.

A rotor 2 composed of three alloy blades is attached to a rotation shaft so as to be rotatable by a bearing. The rotor rotates a generator 3 via a gear, thereby generating power. With the generated power, a motor 5 is rotated, a piston pump 6 connected thereto is driven, and compression air is filled into an air tank 1. At this moment, the compression air pressure is set to 200-250 atmospheric pressure. A clutch works at 250 atmospheric pressure or more to maintain the set pressure. From the air tank, the compression air blows out from two nozzles toward the alloy blades, thereby rotating them for power generation. Alternatively, air may be replaced by water.