Abstract: A compressor includes a housing; a suction region and a discharge region which are formed in the housing in a partitioned manner. The compressor also includes a shaft which is pivotally supported in the inside of the housing. The compressor further includes a compression mechanism which sucks a refrigerant from the suction region and discharges the refrigerant to the discharge region due to a rotational motion of the shaft. The compressor further includes a bypass passage which makes the suction region and the discharge region communicate with each other, a valve element 41 which is capable of closing the bypass passage 40 from a discharge region side, and a spring which biases the valve element toward the discharge region side.