Provided is a piston compressor wherein a centrifugal separation operation can be effectively performed by the rotation of a shaft, to effectively reduce the leakage of oil to the outside of a compressor as well as to promote the cooling of inner components contained in a crank chamber. The piston compressor has a first intake path through which working fluid introduced from an intake port (30) is directly introduced to intake chambers (27a, 27b) without passing through a crank chamber (7), and a second intake path through which working fluid introduced from the intake port (30) is introduced to the intake chambers (27a, 27b) via the crank chamber (7). The second intake path is comprised of an oil separation passage (32) introduced from the crank chamber (7) to the intake chambers (27a, 27b) via holes formed in the shaft, and a bypass passage (33) introduced from the crank chamber (7) to the intake chambers (27a, 27b) through cylinder blocks (1, 2) without passing through the shaft (12).