A compressor of the present invention is provided with a plurality of housing members (a front housing, a cylinder block, and a rear housing) that forms a body, a fastener (a bolt member) for coupling the plurality of the housing members to one another, a drive shaft inserted through the body and coupled to a power source via an electromagnetic clutch, a movable member (a piston) that moves in association with the drive shaft to compress a fluid, a detection body that moves in association with the drive shaft, and a detection part for detecting a rotational state of the drive shaft by means of the detection body. A magnetic sensor having a magnetic impedance element constitutes the detection part. The magnetic sensor is provided on an outer lateral face side of the body and in proximity to the fastener.