To quickly charge each kind of battery by obtaining the difference between the voltage immediately after off of a DC pulse supplied to a secondary battery and the voltage in timing slower than it, and comparing it with a specified reference voltage, and changing the current value of a current pulse.

When a secondary battery 5 is connected to a quick charge circuit 1, an A/D converter 6 detects it, and starts charge. A microcomputer 7 outputs the first current value (10C) to a fixed current source 2. Here, C shows the charge current for one hour of the rated capacity of the secondary battery 5. The microcomputer 7, when a timer 8 measures the on time of one second, instructs off to a current switching circuit 4, and performs the charge of 10C for one second. The microcomputer 7, when 95ms pass away, converts the terminal voltage of the secondary battery 5 from AC to DC 6. Next, the microcomputer 7 turns off a current and gets the differential voltage between the voltage V1 of 5ms or thereabouts and the voltage v2 f 95ms or thereabouts (V1-V2), and compares it with the reference voltage. It repeats the on-off while lowering the 10C value until the differential voltage becomes larger than the reference value. Hereby, each kind of secondary battery can be quickly charged.