PURPOSE: To enable elimination of the need to mount a suction valve, by a method wherein a suction passage, intercommunicating the interior of a cylinder part and a cam plate chamber when a piston is situated at position near a bottom dead point, is formed in a housing, and only a delivery chamber is formed outside the housing.

CONSTITUTION: A suction passage 411 is formed in a position in the vicinity of the bottom dead point of a piston 124 in a compression chamber 213, and the suction passage 411 is formed with plural suction passage holes 414 and a suction groove 413. The plural suction passage holes 414 are formed around a cylinder 123 within a housing 114, the one end thereof is open to a cam shaft chamber 225, and the other end is communicated with the suction groove 413. Thus, the cam plate chamber 225 is communicated with the compression chamber 213 through the suction passage hole 414 and the suction groove 413. As noted above, since the cam shaft chamber 225 and a cylinder 123 are communicated to a compression chamber 213 only through the suction passage 411 formed in the housing 114, a suction valve can be eliminated. Further, only a delivery chamber 214 may be formed outside the housing 114, and thus, a seal between the suction chamber and the delivery chamber can be sharply facilitated.