A high-efficient heat cycle device formed by combining a heat engine with a refrigerating machine, wherein steam generated in a boiler is cooled by a condenser after driving turbine, built up by a pump, and circulated into the boiler in the form of high-pressure condensate. Refrigerant gas compressed by a compressor is passed through the radiating side of a heat exchanger for cooling after driving the turbine to output a work, and built up by a pump to form high-pressure refrigerant liquid. The high-pressure refrigerant liquid drives a reaction water-turbine to output a work and is expanded and vaporized to form refrigerant gas. The refrigerant gas is led into the compressor after being passed through the heat absorbing side of the heat exchanger and the condenser for heating.