PURPOSE: To suitably charge different type batteries by a single charger by controlling a charging current when the batteries are charged between a battery having a large nominal capacity and a battery having a small nominal capacity, and controlling a temperature of the secondary battery in response to a variation per a time unit.

CONSTITUTION: A secondary cell 1 is charged from a constant-current circuit 5 through a charge/discharge switching selector 6. A voltage obtained by measuring secondary cell voltage is input from a terminal voltage measuring circuit 7, a cell temperature obtained from a thermistor 2 is input from a surface temperature measuring circuit 8 and an atmospheric temperature obtained from a thermistor 12 is input from a measuring circuit 13 to a controller 3. The controller 3 contains a CPU, obtains ratios of variations of the voltage, the temperature to a time by data from the circuits 7, 8, 13 and a timer 9 and identifies a type of the connected cell 1. Switching of the selector 6 is controlled in response to the identified result, and discharging of a discharging circuit 4 is controlled to control a charging current. Thus, different types of the cells 1 are suitably charged by one charger.