To provide an inrush current apparatus which can perform boosting charge of a battery by rapid chemical reaction working together with a low voltage charger.

A positive electrode 2 and a negative electrode 3 of a lead battery 1 are subjected to short-circuit repeatedly through a resistor 4 at an interval of 5 sec by means of a timer switch 5. Boosting charge is performed by rapid deterioration of specific gravity of lead battery liquid, together with use of a charger (AC 100V input).