MOTOR DRIVE DEVICE FOR VEHICLES

A lightweight motor drive assembly for a vehicle is provided in which vibration is less likely to occur. The motor drive assembly includes an electric motor (3), a speed reducer (4) configured to reduce the rotation speed output from the electric motor (3), and a differential (5) configured to distribute the rotation output from the speed reducer (4) to right and left vehicle wheels. A rotor (7) of the electric motor (3) includes a spindle (17) rotatably supported by a first bearing (15) and a second bearing (16), and a rotor core (18) mounted on the outer periphery of the spindle (17). The spindle (17) includes a tubular, hollow, rotor core mounting portion (19) having an inner diameter larger than the diameter of a cylindrical first bearing fitting surface (24) on which the first bearing (15) is fitted. A first shaft portion (21) is coupled to an end plate (20) closing the end portion of the rotor core mounting portion (19) on the side of the rotor core mounted portion (19) close to the speed reducer (4).