Abstract: A compressor includes a closed casing having a suction chamber and a discharge chamber. A rotating member is arranged in the casing and has a spiral bore extending along the axis of rotation of the rotating member. The bore has first and second end openings communicating with the suction and discharge chambers, respectively. A spiral internal member is inserted into the bore to rotate relative to the rotating member as the rotating member is rotated by an electric motor section in the casing. In conjunction with an inner surface of the bore, the internal member defines a plurality of closed spaces moving from the first end opening to the second end opening. A fluid in the suction chamber is transported from the first end opening to the second end opening while confined within the spaces, and is then discharged into the discharge chamber. The discharge of the fluid is controlled by a valve mechanism.