A motor-driven compressor comprising: a compression mechanism compressing a refrigerant gas; a rotary shaft rotating to drive the compression mechanism; an electric motor connected to the rotary shaft; a motor drive circuit for driving the electric motor; and a housing assembly in which the compression mechanism, the electric motor and the motor drive circuit are disposed along the axial direction of the rotary shaft, wherein the housing assembly has a first housing and a second housing, wherein the first housing is used for mounting the electric motor and the compression mechanism, and has first and second mounting lugs (45, 46) formed integrally with the peripheral surface of the first housing, wherein the second housing is joined to the first housing for accommodating the motor drive circuit, and has a third mounting lug formed integrally with the second housing, the second housing having a cylindrical shape with one end closed, the second housing including a cover portion, and a cylindrical wall portion extending from the entire periphery of the cover portion, characterised in that the third mounting lug is formed integrally with the cover portion, and wherein the first through third mounting lugs (45, 46, 47) are fastenable to a mounting object on which the motor-driven compressor is to be mounted by means of fastening members (B1, B2, B3), wherein the first and second mounting lugs (45, 46) are located between the electric motor and the compression mechanism in the axial direction of the peripheral surface of the first housing, and wherein the first and second mounting lugs (45, 46) are formed integrally with the first housing at positions of the first housing where the first and second mounting lugs (45, 46) are not lapped over the electric motor and the compression mechanism. a compression mechanism compressing a refrigerant gas; a rotary shaft rotating to drive the compression mechanism; an electric motor connected to the rotary shaft; a motor drive circuit for driving the electric motor; and a housing assembly in which the compression mechanism, the electric motor and the motor drive circuit are disposed along the axial direction of the rotary shaft, wherein the housing assembly has a first housing and a second housing, wherein the first housing is used for mounting the electric motor and the compression mechanism, and has first and second mounting lugs (45, 46) formed integrally with the peripheral surface of the first housing, wherein the second housing is joined to the first housing for accommodating the motor drive circuit, and has a third mounting lug formed integrally with the second housing, the second housing having a cylindrical shape with one end closed, the second housing including a cover portion, and a cylindrical wall portion extending from the entire periphery of the cover portion, characterised in that the third mounting lug is formed integrally with the cover portion, and wherein the first through third mounting lugs (45, 46, 47) are fastenable to a mounting object on which the motor-driven compressor is to be mounted by means of fastening members (B1, B2, B3), wherein the first and second mounting lugs (45, 46) are located between the electric motor and the compression mechanism in the axial direction of the peripheral surface of the first housing, and wherein the first and second mounting lugs (45, 46) are formed integrally with the first housing at positions of the first housing where the first and second mounting lugs (45, 46) are not lapped over the electric motor and the compression mechanism.