PURPOSE: To circulate two pistons in an annulus ring shaped cylinder on which an intake port and a discharge port are provided so that air or gas may be sucked in and compressed so as to provide a gas compressor in which there is neither a reciprocating motion part nor any abrasion part of a prior screw type.

CONSTITUTION: A gas compressor consists of an annulus ring shaped cylinder 10 made of non-magnetism tubular body, an intake port 12 and a discharge port 13, two pistons 20, 20, and deices 30 in which an electromagnetic coil provided in order to move and stop the pistons 20, 20 is used. While one side piston 21 is stopped in a piston stopping position 14 by the device 30 in which the electromagnetic coil is used, the other side piston 22 is moved from the downstream side of the intake port 12 toward the discharge port 13 by the device 30 in which the electromagnetic coil is used. It is thus possible to compress air or gas in a cylinder space contracted forward one side piston 21.