Abstract: A method of supplying lubrication oil to a two-stage screw compressor is disclosed in which a low-pressure stage screw compressor and a high-pressure stage screw compressor are integrally constructed. A compression space is formed by a male rotor and a female rotor, and operation gas is fed for compression to the compression space. The method prevents degradation of volumetric efficiency caused by return of lubrication oil, coming from a bearing and a shaft sealing device, to the low-pressure stage screw compressor, and as a result, refrigeration capacity is improved and the amount of the lubrication oil is reduced.