In a housing 1, 2, a rotor 11 is secured to a drive shaft 6 and a sleeve 12 is supported movably. A rotary swash plate 14 is tiltably supported on the sleeve 12 and is coupled to the rotor 11. Coupled to the rotary swash plate 14 are pistons 8 which move in the respective bores 9. A fluid is supplied to each bore 9 from a suction chamber 20, and a fluid compressed by each piston 8 is discharged to a discharge chamber 21. A control valve 25 controls the difference between the pressure in the suction chamber 20 and the pressure in a crank chamber 5 to change the inclination angle of the rotary swash plate 14, so that the discharge displacement of a compressor becomes variable. In the housing 1, a spool 32 is movably provided while enclosing the drive shaft 6. With the spool 32 entered in the crank chamber 5, when the sleeve 12 engages with the spool 32, the movement of the rotary swash plate 14 is restricted to the position that sets the discharge displacement of the discharge chamber 21 to a predetermined restricted displacement. By supplying the pressure in the discharge chamber 21 via a pressure supply passage 35 to retract the spool 32 from the crank chamber 5, the rotary swash plate 14 is permitted to move to the position where the discharge displacement to the discharge chamber 21 becomes zero.