To improve the demist-performance by making tilt-rising of a swash plate favorable when the compressor is started at a low outside air temperature.

When the compressor is started when the outside air temperature is low, the flow rate of a refrigerant flowing into a refrigerant suction chamber 7 is controlled to be reduced by a pressure regulating means 30 to be in a state where the amount of a discharged refrigerant is lowered. Since a pressure regulating valve 54 provided in an extension chamber 26 in the downstream of a refrigerant discharge chamber 8 is in a closed state to obstruct the outflow of refrigerant from the refrigerant discharge chamber 8, pressure-rise of the refrigerant discharge chamber 8 is performed quickly, and the tilt-rising of a swash plate 15 by control of the pressure regulating means 30 is performed quickly. The amount of the discharged refrigerant is thus increased to improve the demist-performance.