PURPOSE: To obtain large driving power with small electric power by fixing plural number of permanent magnetic plates on the piston rod of a piston type reciprocating compressor with compressing chambers on both left and right sides and fitting electromagnets, of which polarities are successively changed, between the magnetic plates.

CONSTITUTION: Refrigerant gas from the evaporator (not indicated in the figure) goes into the right cylinder 2 and the left cylinder 3 which constitute the cylinder 1 through the gas suction ports 7, 7' of said cylinder 1 and reaches the compressors 5, 5' through the switching valve 9 of the pistons 10, 10' while cooling the driving part 8. Refrigerant gas is compressed here and transferred by pressure to the condenser through gas feeding pipe 24. At this time, by exciting the electromagnets 18, 19 by converting direct current from the battery power source into alternation current at the polarity converting drum, repulsion force and adsorption force are alternatively given to three permanent magnetic plates 11W13 which are incorporatedly connected by the spacing cylinders 15, 15'. By this constitution, the magnetic plates 11W13 are horizontally moved to give reciprocating motion to the pistons 10, 10' through the rods 14, 14'.