A refrigerant compressor having pistons reciprocated in respective cylinders by a wobble plate driven by an input rotor which is secured on a drive shaft, in which improved refrigerant gas flow within the housing is achieved. A balance hole is provided for returning the blow-by gas, which is leaked from the cylinders through the gaps between the cylinders and pistons to the crank chamber, to the compressor suction chamber from the crank chamber. The balance hole comprises a first fluid passageway formed in a front end plate and a second fluid passageway connected between the first fluid passageway and the suction chamber. One end of the first fluid passageway opens into a hollow portion formed on a axial end surface of the input rotor. The rotor is formed with at least one opening at its outer peripheral surface which communicates between the crank chamber and the hollow portion. Therefore, the amount of lubricating oil which is discharged together with the returned blow-by gas through the balance hole is reduced.