A motor-driven compressor has a compression mechanism, a rotary shaft, an electric motor, a motor drive circuit and a housing assembly. The compression mechanism, the electric motor and the motor drive circuit are disposed along the axial direction of the rotary shaft in the housing assembly. The housing assembly has first and second housings. The first housing mounts the electric motor and the compression mechanism. The first housing has first and second mounting lugs formed integrally with the peripheral surface of the first housing. The second housing is joined to the first housing for accommodating the motor drive circuit. The second housing has a third mounting lug formed integrally with the second housing. The first through third mounting lugs are fastened to a mounting object to which the motor-driven compressor is to be mounted by means of fastening members.