A charging device supplies charge current to a battery group having plural secondary batteries connected in series to perform charging. In the charging device, a discharge route circuit for discharging charge current to be supplied to the secondary battery when the battery voltage of the secondary battery exceeds a predetermined voltage while charging is provided to every secondary battery. Also provided is a cut-off circuit for cutting off the discharge route circuit from each secondary battery after charging is completed. Discharge at a discharge route circuit is suppressed and energy efficiency is increased.
