To provide an in-wheel generator as a vehicle-mounted generator, which can eliminate the increase of volume and weight and the loss of energy by a power transmission member such as a gear, a pulley, etc. for obtaining torque from the axle or the engine output shaft of an automobile.

This in-wheel generator comprises a rotor which is fixed to the wheel disc of the wheel of an automobile and a stator which is fixed to the bearing of a wheel, and at least one part each of the above rotor and the stator is arranged in the space surrounded by the rim of a wheel and the above wheel disc.