To easily position a movable assembly by constituting to compress operating fluid by moving the movable assembly in reciprocation with a variable capacity compression chamber in a housing by operation of a linear motor having a fixedly and movably constituted element in a housing.

A reciprocating motion compressor 80 is provided with a cylindrical pressurized motor housing 82 having housing partition 84a and 84b, a barrel of a fixed central piston 86 is fixed to the housing 82. The piston 86 is provided with an axial penetrating port 90 as a delivery passage which is rapidly extended. Movable cylinders 94a, 94b moved in reciprocation by the linear motor are fitted to fixing sleeves 93a, 93b which are integrally formed with the piston 86, and thereby, compressor chambers 98a, 98b are partitioned. The linear motor is provided with cylindrical movable armatures 104a, 104b made of ferromagnetic material fixed to outer surfaces of the cylinders 94a, 94b.