PURPOSE: To change the position of upper dead point of a piston and change the discharging capacity of the compressor by a simple structure by a method wherein a moving means, moving first shaft, on which a swash plate is formed, into the axial direction thereof, is provided in the compressor.

CONSTITUTION: When the temperature of air from a blow-off port of an evaporator is judged that it is higher than a set temperature by a sensor and a judging device, a discharging chamber 53 is communicated with first pressure chamber 61 through a solenoid three-way valve 12. A pressure in the first pressure chamber 61 is introduced into the second pressure chamber 62, the first pressure receiving surface 81a and the second pressure receiving surface 82a of a plunger 81 receive pressure and they are energized toward left. First shaft 8 moves leftward against the energizing force of a spring 13 and a thrust force and first stopper surface 82a abutts against a thrust bearing 14a. As a result, the swash plate 8a, formed on the first shaft 8, is moved and the upper dead point of the piston 2 moves to the uppermost position in a cylinder bore 1a. Accordingly, the discharging capacity of the compressor 100 gets to its maximum.