To improve responsiveness of a displacement control valve device for a variable displacement cam plate type compressor.

A pilot valve 35 for adjusting the flow quantity of refrigerant gas, flowing into an accumulator 33, according to the pressure of an inlet 3a is provided with a cutout 35a serving as a pressure regulating passage for making refrigerant gas in the accumulator 33 escape to lower the pressure of the accumulator 33. When the pressure of the inlet 3a becomes low, the pilot valve 35 is opened, and high pressure refrigerant gas flows into the accumulator 33 from a discharge chamber 12 through a high pressure passage 34. Since a valve element 31 is not provided with a pressure regulating passage, the pressure buildup speed of the accumulator 33 is high, and the valve element 31 ascends in an instant to reduce valve opening. When the pressure of the inlet 3a becomes high, the pilot valve is closed to cut off the inflow of high pressure refrigerant gas to the accumulator 33. At this time, the accumulator 33 is communicated with a passage through the cutout 35a of the pilot valve 35, so that refrigerant gas in the accumulator 33 escapes to the inlet 3a through the cutout 35a of large passage cross-sectional area. The pressure of the accumulator 33 is lowered, and the valve body 31 descends in an instant to increase valve opening.