PURPOSE: To induce an electromotive force in a coil and to charge a storage battery by fixing one of a permanent magnet or an electromagnet to an electric device body, and oscillatorily supporting the other in a direction in which a pole and a pole part are separated or approached.

CONSTITUTION: An electromagnet 3 is fixed to an electric device body 4, and a permanent magnet 1 is so supported to its pole 5a as to separate from or approach the pole 5a. A magnetic flux passing through a core 5 is varied by using a movement of stopping upon vibration of the body 4 and the electromagnet 3 by an external force during carrying and reception of an inertial force responsive to the acceleration of vibration of the body 4 and the electromagnet 3 by the magnet 1. Thus, an electromotive force is induced in a coil 6 to charge a storage battery 7.