bearing 15 and the sub-bearing 16. A roller 18 having a predetermined thickness is evenly formed around the outer circumferential surface of the eccentric shaft 17. An internal circumferential surface of the cylinder 19 is formed outside the roller 18. Here, the outer circumferential surface of the roller 18 travels along the internal circumferential surface of the cylinder 19. The center of the cylinder 19 is eccentrically formed against the center of rotation of the roller 18. Meanwhile, the outer circumferential surface of the cylinder 19 is fixedly affixed to the inner circumferential surface of the body 10 while maintaining a predetermined air gap therebetween. A bolt 20 is disposed in order to secure the main bearing 15, the sub-bearing 16 and the cylinder 19. Here, since theinternal center of the cylinder 19 corresponds to the center of the shaft 13 and the rotation center of the eccentric crank shaft 17 is eccentrically formed against the shaft 13, as the shaft 13 rotates, the roller 18 eccentrically travels along the inner circumferential surface of the cylinder 19. Accordingly, as the roller 18 rotates, a predetermined space is generated inside the cylinder 19. Meanwhile, a vane groove 21 is formed at a predetermined portion of the cylinder 19. A vane 22 is slidably inserted into the vane groove 21. Here, when the eccentric crank shaft 17 is positioned at the top dead point inside the cylinder 19, there is defined a suction chamber 23 at right space which is defined by the outer circumference of the