A motor-driven compressor has a compression mechanism, a rotary shaft, an electric motor, a motor drive circuit, a connecting terminal 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 having first through third housings. The first housing is used for mounting the electric motor and the compression mechanism. The second housing has a terminal mounting portion for fixing the connecting terminal. The first and second housings have fastening portions at the radially peripheral portion thereof. The third housing is joined to the second housing to form an accommodation space for accommodating the motor drive circuit. The closed casing is formed by fastening the fastening portions of the first and second housings by means of a first bolt and connecting the second housing to the open end of the first housing.