PURPOSE: To enable to miniaturize the device by a method wherein a valve body is assembled in the vicinity of the discharge and suction ports of a cylinder so as to change-over from/to the high pressure outlet to/from the low pressure inlet.

CONSTITUTION: The changing-over of cycles is performed by energizing a solenoid valve 33 so that high pressure refrigerant gas flows through a high pressure outlet pipe 34 into a cylinder 32 and pushes up a piston 31A, a rod 31B, and a movable valve 3 in order to change-over cycles. At this time, a low pressure communication pipe 35A serves to make the actuation of the piston 31A and the like smooth by sucking the refrigerant gas in the cylinder 32 therethrough. And yet, when the solenoid valve 33 is closed, the piston 31A, the rod 31B, and the movable valve 3 return themselves to their original positions. In such a manner as mentioned above, a complicated piping, which may be lain around a four-way valve, is eliminated and the miniaturizing of the device can be resulted.