A battery charging controller according to the present invention controls battery charging in response to a charging-control signal sent from a CPU, and includes an starting controller which is started upon a detection of an insertion of an AC adapter, and which then starts a regulator at a predetermined timing by using a regulator control signal. The regulator is started upon a detection of the regulator control signal, and thereafter starts the CPU by using an starting signal. The CPU is started upon a detection of the starting signal.