PURPOSE: To increase rigidity of a plate on the moving side to disperse a resonance point and to improve durability by increasing the thickness of the expandable part on the moving side of a bellows to a value higher than that of the expandable part on the fixed side, in a device to effect inflow and outflow of fluid through expansion and contraction of the bellows.

CONSTITUTION: When an input shaft 9 is rotated with the aid of a prime mover and a rod 8 is vertically driven through a roller 20 on an eccentric shaft part 13 located to a shaft end, a bellows 4 is expanded and contracted through a moving support 6. Fluid sucked through a suction port 19 during expansion of the volume of a chamber 7 is delivered through a delivery port 21 during contraction of the volume of the chamber 7. In this case, the bellows 4 (41) has an expansion and contraction part composed of a thin section part 41a on the side fixed to a fixed support 5 and a thick section part 41b on the side fixed to a moving support 6. An expansion and contraction part may be formed such that thickness is increased orderly or in a stepped manner from a fixed end toward a moving end. This constitution reduces the generation of resonance energy of the whole of the bellows and improves durability.