A charging device has an electric accumulator (20) formed by a plurality of series-connected electric accumulator cells (E1, E2, . . . , En), one electrode of any one of the electric accumulator cells being used as a reference potential of the electric accumulator (20); at least one capacitor (C1) having one end fixed to the potential of one electrode of each of the electric accumulator cells (E1, E2, . . . , En) or fixed to the potential of the other electrode of any one of the electric accumulator cells (E1, E2, . . . , En) through a rectifying means (D11, D12); and a periodical power source (30) connected between the capacitor (C1) and the reference potential of the electric accumulator to generate repetitive signals.