PURPOSE: To recover cold energy to a maximum by a method wherein in a recovery device for energy generated during gasification of liquefied gas, a device to heat- exchange with gas to be cooled after boosting of liquefied gas, and a device to heat- insulate and expand liquefied gas and heat-exchange with gas to be cooled after rotation of a turbine are provided.

CONSTITUTION: After liquefied nitrogen gas LN2 bled from a liquefied nitrogen gas tank A is boosted with the aid of a pump B, it is heat-exchanged with oxygen gas GO2 by means of a heat exchanger C for gasification. The gasified nitrogen gas is recovered as a power through running of a generator E coupled to a turbine by heat- insulating and expanding the gas by means of a middle pressure expansion turbine D. After the nitrogen gas is heat-exchanged with oxygen gas GO2 by means of the heat exchanger C again for gasification, it is heat-insulated and expanded by a low pressure expansion turbine F, by running the generator G coupled to the turbine, it is recovered as a power, and it is heat-exchanged with oxygen gas GO2 by the heat exchanger C again to discharge it as ordinary temperature nitrogen gas GN2. The oxygen gas GO2 is heat-exchanged with the liquefied nitrogen gas LN2 by means of the heat exchanger C to produce liquefied oxygen gas LO2, which flows to a liquefied oxygen tank H. This constitution enables the increase of cold recovery energy.