PURPOSE: To prevent overcharge, overdischarge of a nonaqueous soluble solvent type secondary cell.

CONSTITUTION: Voltage detectors 17, 18 for detecting terminal voltages of individual cells 14A, 14B connected in series with one another, are provided, and switch means 16 is provided in series with a cell 14 between a common terminal 11 and a charging terminal 13. The means 16 is opened based on an output of the detector 17 or 18 of the corresponding cell when a terminal voltage of at least one cell 14A or 14B exceeds a cell designing voltage at the time of charging to cut OFF a charging current. A voltage detector 19 for detecting a voltage across the cell 14 connected in series, is provided, and switch means 15 is provided in series with the cell 14 between the terminal 11 and a discharge terminal 12. The means 15 is opened based on the output of the detector 19 when a voltage across the cell 14 becomes a set voltage or lower to cut OFF the charging current.