A suction throttle valve of a variable displacement compressor having a compressor housing includes a suction chamber, a crank chamber, an inlet, a suction passage, a valve body, a valve housing, an urging member, a valve chamber, and a communication hole. The valve body is provided for adjusting an opening area of the suction passage and movably arranged in the suction passage. The urging member urges the valve body in the direction that decreases the opening area of the suction passage. The communication hole is provided for connecting the suction chamber to the valve housing. An opening area of the communication hole is variable in accordance with the movement of the valve body. Accordingly, the opening area of the communication hole becomes maximum during the maximum displacement operation of the compressor and becomes reduced during the intermediate displacement operation of the compressor.