A compressor includes a housing body and a drive shaft rotatably supported in the housing body. A swash plate is mounted on the swash shaft. Cylinder bores are defined in the housing body. Pistons are operably coupled to the swash plate and are disposed in the cylinder bores. The swash plate converts a rotation of the swash shaft to a reciprocating movement of the pistons along an inner surface of the cylinder bores. Each piston compresses gas supplied from a suction chamber to the associated cylinder bore and discharges the compressed gas to a discharge chamber. Deformation of the inner surface of each cylinder bore is reduced by utilizing pressure of the gas compressed in the cylinder bore.