PURPOSE: To form a compressor to small size and light weight, by constituting the compressor to a mechanism in which a free piston in a hollow cylindrical rotor is silidably moved by solenoid coils in the periphery of the cylindrical rotor while the cylindrical rotor itself is rotated by the rotating magnetic field of a motor coil provided in the periphery of the cylindrical rotor.

CONSTITUTION: A free piston 2 is located in a rotor 1 and laterally slided by conducing an electric current in solenoid coils 4, 5. Gas is sucked by rightward movement of the piston to a suction chamber 25 through a suction path 12 and suction valve 13, then transferred by leftward movement of the piston to a compression chamber 26, and then compressively delivered again by the rightward movement of the piston via a delivery valve 15 and delivery path 11. Here an electric current is conducted in a motor coil 3, then the rotating magnetic field is generated to rotate the rotor 1 and rotate heat exchangers 18, 19 mounted to both end shafts 9, 10 , thus airs 30, 31 are sucked, exchanged with heat and blown out.