To provide a constant current timer control for a battery charger not easily causing overcharging which does damage to the battery and greatly shortens its life as with prior arts where the time period of the charging is the same regardless of the amount of remaining electric capacity, and further is low priced, not by just attaching a complicated structure counter circuit and controlling by counter value making the cost of control high when calculated from the cost of the device, which would defeat the purpose.

In a charger that performs charging operation under constant current timer control, the charging operation is adjusted according to the remaining electric/capacity in a cost-saving manner. The charger prevents the difference between the counter value and the remaining capacity from exceeding a predetermined value.