PURPOSE: To prevent the seizure of bearings of a compressor, by drawing oil in a motor chamber to a crank chamber by the function of an ejector that is obtained by extracting a part of oil supplied to bearings by way of forced feed and using the same as working fluid.

CONSTITUTION: A part of oil supplied to the region of a bearing 10 via an oil passage 11 formed in a crank shaft 15 forcibly by means of an oil pump or the like is returned to a crank chamber 2. Said part of the oil is branched from an inlet passage 26 into an oil return pipe 29 and then ejected into the crank chamber 2 from a nozzle 28. On the other hand, oil returned to a motor chamber 3 together with coolant gas and oil leaked into the motor chamber 3 from the gap of the bearing 10 are both drawn into a suction port 30 of an ejector and returned to the crank chamber 2 together with oil ejected from the nozzle 28, so that the bearing can be protected from generating seizure.