A variable displacement compressor allowed to use an electromagnetic control valve not requiring a large solenoid force, comprising an electromagnetic proportional flow control valve (12) installed in a refrigerant flow passage (13) from a discharge chamber (10) to a condenser, a constant differential pressure regulating valve (14) installed in the refrigerant flow passage from the discharge chamber (10) to a crank chamber (1), and a fixed orifice (15) installed in a refrigerant flow passage from the crank chamber (1) to a suction chamber (9), wherein different pressures (Pd, Pd') produced across the electromagnetic proportional flow control valve (12) are sensed by the constant differential pressure regulating valve (14) to regulate the pressure led into the crank chamber (1), whereby, since the constant differential pressure regulating valve (14) controls a pressure (Pc) in the crank chamber (1) so that the pressure difference of the refrigerant across a restrictor with an opening set by the electromagnetic proportional flow control valve (12) becomes constant, the flow (Qd) of the discharged refrigerant becomes constant regardless of a variation in rotational speed of an engine, and since the pressure difference can be controlled by a small solenoid force, the size of the compressor can be reduced.
