To provide a device for continuously increasing pressure of low-pressure gas to high pressure without using an adiabatic compressor, since use energy reduction is required for a refrigeration cycle device and a steam boiler.

With a pressure vessel in which a suction port for low-pressure gas is disposed at a lower part and a discharge port for high-pressure gas is disposed at a high part and by a heater 5 having a heating heat source, gas is heated. Gas having become lightweight is raised to produce negative pressure inside the pressure vessel, thus making the heater continuously suck low-pressure gas. Consequently, the pressure of the low-pressure gas can be raised continuously. Further, by exchanging heat between a low-temperature refrigerant returned from the evaporator 4 and a high-temperature refrigerant from the condenser 1, heating efficiency is improved.