To restrain battery charging amount in a hybrid automobile from reaching a lower limit or an upper limit.

When a battery ECU decides that actual charging amount reached the lower limit of an adequate range on the basis of I-V characteristics (S55), the battery ECU performs calibration to decrease the charging efficiency η, in accordance with difference between the estimated charging amount and the actual charging amount (S60). When the upper limit decision is established (S65), the battery ECU performs calibration to increase the charging efficiency ηin accordance with the above difference (S70). After that, reset process for making the estimated charging amount to match with the actual charging amount is performed, and integration (S50) of the charging and discharging amount is again started by using a new charging efficiency η.