To provide a battery management system achieving standardization of charging conditions set for an external charger controller, thereby simplifying the configurations of a charger and the charger controller relating to the output control of the charger, and enabling further improvement in accuracy of the output control.

A charging condition setting part (51A) sets charging conditions according to the actual charging characteristics of a secondary battery (41). For example, the upper limit value of the battery voltage is lowered by about 0.05 V/cell every time the predicted battery capacity decreases by about 5% of its initial value. A battery status correcting part (51B) monitors respective measured values of a current detecting part (44), a temperature detecting part (45) and a voltage detecting part (46), and, for example, increases the measured value of the battery voltage by the ratio of the standard value to the actual upper limit value. A communicating part (51C) notifies the charger controller (32) of the measured value of the battery voltage and so on corrected by the battery status correcting part (51B). Based on the corrected measured value of the battery voltage and so on, the charger controller (32) makes the output of the charger (31) match the standard charging conditions.