A variable displacement compressor includes a rotary valve (40) which can rotate synchronously with a drive shaft (15). The rotary valve (40) includes a center hole (42) with one end closed and with the other end in constant communication with a suction chamber (26), and a communicating hole (43) intermittently provide a fluid communication between the center hole (42) and a gas extracting passage (32) extending from a crank chamber (14) along with the rotation of the rotary valve (40). The amount of refrigerant gas flowing back from the crank chamber (14) to the suction chamber (26) through the gas extracting passage is reduced by exactly the amount of the refrigerant gas which can flow through the gas extracting passage (32) unless it is closed by the rotary valve. Therefore, even if the sectional area of the gas extracting passage (32) is increased to an extent of being able to prevent sludge and other foreign matter from clogging it and ensure the processing accuracy and productivity, the increase of the amount of gas fed to the crank chamber at the time of transition from a large displacement operation to a low displacement operation, and the increase in the power loss of the compressor, can be suppressed.