PURPOSE: To prevent drop of brightness of a lamp due to voltage drop during the running at the night by mounting a rotor to a rotating body and a stator to a bracket to supply the generated power of the stator to a plurality of electromagnets through a commutator.

CONSTITUTION: A bracket 1 is composed of a cylindrical circumferential wall portion 11 which is larger in diameter than an internal circumferential wall portion 33 of a rotating body 3 and a ring shaped bottom portion 12 formed at an aperture end portion of such cylindrical circumferential wall portion 11 and an electromagnet 2 is provided projected, in the plural number, in the same pitch at the external circumferential surface of the circumferential wall portion 11 of the bracket 1 and is also provided opposed to the internal circumfetential portion 31 of the rotating body 3 keeping a certain gap therebetween. Moreover, a rotor 4 is formed of a permanent magnet and is attached to an internal bottom portion 34 of the rotating body 34. A stator 5 is formed of a stator core 51 and a stator coil 52 and is provided opposed to the rotor at the bottom portion 12 of the bracket 1. As a result, a current is not supplied to a coil formed of an electromagnet from a battery and brightness of lamp is not dropped even the electromagnetic retarder is used.