To provide a technology for continuously converting low-pressure steam to high-temperature high-pressure steam, since it is required to reduce energy used in refrigerating cycle devices and steam boilers and provide devices for continuously pressurizing gas from low pressure to high pressure without using adiabatic compressors and it is known that steam boilers generate steam from liquid water and thus use energy can be reduced by generating steam beforehand and supplying vaporization heat from outside by heat exchange.

Gas is heated by a heater 11 including a pressure container 7 in which a suction port for low-pressure gas and a discharge port for high-pressure gas are disposed on a lower side and a higher side, respectively, and a heating heat source. The gas whose weight is reduced is lifted to generate negative pressure within the pressure container 7 and the low-pressure gas is continuously sucked to the heater 11. As a result, the low-pressure gas can be continuously pressurized, and heating efficiency can be improved by performing heat exchange.