PURPOSE: To prevent generation of environmental pollution by reutilizing power gas which collides with the blade of a turbine rotor by a power gas generator cyclically by reducing pressure in a pressure reducing part.

CONSTITUTION: A rotor housing 12 consists of a first casing 12a, a second casing 12b, and a side cover 12c, the first casing 12a is provided with a cylindrical operating chamber 16, and a turbine rotor 14 is rotatably housed in the operating chamber 16. A plurality of blade 14a is provided on the outer circumference of the turbine rotor 14, power gas collides with the blades 14a, and colliding power gas is reutilized by a power gas generator 20 cyclically by reducing pressure by a pressure reducing part 18. It is thus possible to prevent earth environment failure completely since environmental pollution such as exhaust gas is completely generated.