To provide a motor-driven blower which keeps fixing parts of a rotor-supporting plate inserted along the inside peripheral surface of a case body and fixed to increase the blowing efficiency.

The motor-driven blower is provided with the fixing parts 46 on both ends of a frame 32 for supporting the armature of the motor. The fixing parts 46 are fixed by being inserted along the inside peripheral surface of a nearly cylindrical body-frame 31. When compared with the case in which both ends of the frame are fixed by screws, etc. to a flange of the body frame, protrusions of screws, etc. are not made to the guide airway in the rear of a straightening plate. Thus, airway resistance as well as turbulence of the air straightened by the straightening plate can be restrained to improve the air-supply efficiency.