A capacity type refrigerant compressor having a compression chamber in which a refrigerant introduced from a suction system is compressed and discharged as a compressed high pressure refrigerant, and an oil-separating and lubricating system for lubricating an interior of the compressor by an oil separated from the compressed refrigerant, which has an oil-separating unit to separate the oil from the compressed refrigerant, an oil-storing chamber storing the separated oil, an oil-supply passage to supply the oil from the oil-storing chamber to the suction system, a pressure-operated valve arranged in the oil supply passage to regulate an amount of flow of the oil, which includes a valve chamber and a movable valve spool in the valve chamber to control a communication between the upstream and downstream of the oil-supply passage. The valve spool element moves in response to a change in a pressure differential between pressures in the compression chamber and the suction system, and blocks the oil flow in the oil-supply passage when the pressure differential is overcome by a spring force arranged in the valve chamber.