A variable displacement swash-plate type compressor has a swash plate rockably carried by a shaft, and a spool for changing the angle of tilt of the swash plate and also the position of the center of the swash plate, thereby to vary the displacement of the compressor. The compressor has a control valve which determines a control pressure to be supplied to a control pressure chamber behind the spool, between the level of a low-pressure introduced from a low-pressure side of the compressor and a high-pressure introduced from a high-pressure side of the compressor.
