To provide a structure for a low-cost and highly efficient generating device in regard to supplying of heat source near an ordinary temperature, to improve generating efficiency by a new cogeneration system, and provide a generating device saving on power and using clean energy.

A liquid heating medium 3 in an heat exchanger 1 for absorbing heat of an external heat source vaporizes and expands while absorbing heat from the outside. A turbine 6 is rotated by expansion force and power is generated by a generator connected with a rotary shaft of the turbine 6. Then heat of the heating medium 3 is rapidly absorbed as heat of vaporization by a liquid heating medium 3 in a heat exchanger 2 for cooling condensation and the heating medium 3 is cooled, condensed and sent to the heat exchanger 1 for absorbing heat of the external heat source by a circulating pump 5. The liquid heating medium 3 in the heat exchanger 2 for cooling condensation absorbs heat from the heating medium bringing heat from the heat exchanger 1 for absorbing heat of the external heat source, and it vaporizes and expands. It rotates a turbine axial-flow compressor 4 by expansion force, and at the same time it is compressed and becomes a heating medium of high temperature high pressure gas. Then it is cooled and condensed by a condenser and sent to the heat exchanger 2 for cooling condensation by a circulating pump 5.