To hold reliability in charge/discharge operation by stopping the charge/ discharge operation by a charge/discharge practicing part when abnormality of the charge/discharge operation is caused by abnormality of a battery, and stopping the charge/ discharge operation by cutting off a relay arranged in an electric current passage of a charging/discharging current when the abnormality is caused by the charge/discharge practicing part.

In the case an apparatus in a device is abnormal, when abnormality of one's own function is detected by an electric current and voltage abnormality detecting means and a disconnection detecting means inside of respective apparatuses in a charge/discharge part 13, a measuring part 15 or a charge/discharge control part 16, a contact point signal is transmitted to a control management part 17 from the respective apparatuses. The control management part 17 receiving the contact point signal opens an isolating switch 14 to cut off an electric current supply line to finish charge/discharge operation. In the case where a battery is abnormal, when detecting it, an electric current input/output stopping sequence for stopping input/output of a charging/discharging current and a supply line cutoff sequence for forcedly cutting off a supply line of the charging/discharging current are parallelly performed to stop the charging/discharging current.