PURPOSE: To provide a device for two-stage compression refrigeration which enables the operation to be free of an unbalance in oil between the higher-stage compressor and the lower-stage one.

CONSTITUTION: The refrigerant discharged from the lower-stage compressor 1 is compressed again by the higher-stage compressor 2 and discharged. There are provided an oil separator 6 and an oil-return circuit 21, the oil separator 6 for separating the oil from the refrigerant discharged from the higher-stage compressor 2 and the oil-return circuit 21 for returning the oil from the oil separator 6 to each of the higher-stage compressor 2 and the lower-stage compressor 1.