PURPOSE: To realize improvement in the number of charging and discharging cycle times by performing discharging and charging for each cell in a storage battery with a plurality of cells placed in series connection, conerning charging and discharging of the storage battery.

CONSTITUTION: A discharger 18 comprises a plurality of discharging terminals 13 to which a storage battery 12 is attached and having a plurality of storage battery cells 11 with each of which has a positive/negative terminal 10, a voltmeter 14, a load resistor 15, switches 16 and a discharging control unit 17 and the discharging terminals 13 draw out the positive/negative terminals 10 of all the storage battery cells 11. Each changeover switch 16 selects the discharging terminals connected to the positive/negative terminals 10 of the target storage battery cells 11 one by one by means of control of the discharging control unit 17, discharging is performed for each cell by a load resistor 15, and when all storage battery cells are discharged 11, and the storage battery 12 and the discharger 18 and electrically separated by the switch 16 and discharging is finished.