A refrigerant compressor for automobile air-conditioning system is disclosed. The compressor comprises a front end plate member and a cylindrical casing attached to an end surface of the front end plate member. A polygonal shaped portion is formed on the outer peripheral surface of the front end plate member and a plurality of projections are formed on an opposite end of the housing from the polygonal shaped portion. The end surfaces of the projections are aligned on the same plane with each end surface of polygonal shaped portion. The end surfaces of the projections and the polygonal shaped portion have tapped holes for attaching mounting brackets. Therefore, a variety of suitable mounting arrangements can be used to mount the compressor and the mounting angle of the compressor can be adjusted.