A reciprocating refrigerant compressor having a cylinder block provided with a plurality of cylinder bores in which a refrigerant gas sucked from a suction chamber is compressed to be subsequently discharged into a discharge chamber, a valve plate having suction ports through which the refrigerant gas is sucked into the respective cylinder bores and discharge ports through which the compressed refrigerant gas is discharged, a suction valve attached to one end face of the valve plate, a discharge valve attached to the other end face of the valve plate, a housing assembly attached to the cylinder block and having the suction and discharge chambers, and a sealing unit arranged in one of boundaries between the end face of the cylinder block and the suction valve, and between the suction valve and the valve plate to provide an annular sealing portions around each of the bore ends of the plurality of cylinder bores. The typical sealing unit is formed of a metallic base plate and elastic rubber membranes attached to the opposite faces of the metallic base plate.