A refrigerant compressor comprising a balance hole communicating between a crank chamber and a suction chamber for returning the blow-by gas in the crank chamber to suction chamber, is provided with an oil separating member in a discharge chamber to separate oil in the compressed refrigerant gas. The separated oil is accumulated in an accumulating zone in the discharge chamber and returns to the crank chamber through an oil flowing passageway which communicates between the accumulating zone and the crank chamber thereby to reduce the oil leakage into the refrigerant circulating system.