To fully charge batteries in a shortest time without causing damages to them.

This device charges the batteries of an electric vehicle 1 which travels with an electric motor 5 driven by 'n' pieces of batteries B1 to Bn connected in series. In this case when the voltage across terminals of each battery Bi (1≤i≤n) reaches a given level or higher, charging current to the battery Bi is bypassed and a battery monitor BMi, which outputs signal to indicate that the charging current was bypassed, is connected in parallel. Furthermore, by controlling an inverter 2 formed the number battery Bi to which no charging current is supplied, charging current (regenerative current) to be supplied from the electric motor 5 to the batteries Bi when the electric vehicle 1 is braked is controlled, to prevent the overcharge of the battery Bi and the supply of excessive charging current. In addition, a function can be added to the battery monitor BMi for maintaining the charging current at the level close to a maximum permissible charging current, which does not damage the battery Bi from the temperature of the electrolyte of the battery Bi.