PURPOSE: To produce a compact compressor by coupling a piston rod in parallel with the drive shaft to a rotatable bearing ring provided on the outercircumference of inclined disc swash plate rotatable with the drive shaft thereby reciprocating the piston through the rod.

CONSTITUTION: Upon driving of drive shaft 9 through an engine, a swash plate 19 secured through a key 20 to said drive shaft 9 will rotate along the innercircumference of a bearing ring 21. Since the swash plate is inclining, a spherical bearing 23 will move up and down sequentially with different phase. Consequently, each piston rod 29, 30 engaged through an annular groove 33 will reciprocate sequentially with different phase to compress gas sucked into the cylinders 17, 18 and discharge through a discharge port.