A variable-delivery refrigerant compressor wherein the delivery of a compressed refrigerant is adjustable by an actuator which is movable with a discharge pressure of the compressor between a first position at which plural discharge valves corresponding to compression chambers are rendered operative, and a second position at which at least one of the discharge valves is rendered inoperative. A pilot switch valve is disposed in a passage through which the discharge pressure is applied to the actuator. The switch valve controls a supply of refrigerant of the discharge pressure to the actuator such that the actuator is placed in the first position while a suction pressure of the compressor is relatively high, and in the second position while the suction pressure is relatively low.