IN-WHEEL MOTOR DRIVE DEVICE

An in-wheel motor drive device includes an electric motor (1) to drive a wheel, a wheel support bearing assembly (5) to support the wheel, and a speed reducer (2) to reduce the rotation of the electric motor (1) and then to transmit it to the wheel support bearing assembly (5), and a lubricant oil is supplied under pressure by an oil pump to the speed reducer (2) to be lubricated. The use is made of a temperature detector (Sa) to detect the temperature of the lubricant oil or the electric motor (1) and an output limitter (49) to limit the output of the electric motor (1) in the event that the temperature detected by the temperature detector (Sa) is not higher than a predetermined threshold value.