A control valve controls the displacement of a variable displacement type compressor. The compressor includes a crank chamber, suction chamber, a bleed passage, and a supply passage. The control valve has a supply side valve, a transmission rod, and a relief side valve. The transmission rod connects the relief side valve with the supply side valve. The relief side valve includes a passage chamber constituting part of the bleed passage. The passage chamber is separated into a first area, which is connected to the crank chamber, and a lower area, which is connected to the suction chamber. A pressure sensing member moves the relief side valve body in accordance with the pressure in the upper area. The effective pressure receiving area of the sensing member is substantially equal to the cross sectional area of the passage chamber that is sealed by the relief side valve body.