To provide an electric voltage balance controller capable of smoothing electric voltage variations in a battery pack that become larger between battery cells in the late step of charging.

An electric voltage balance controller 100 identifies a target battery cell for voltage balancing process to be held in the next charging operation on the basis of the variation in cell voltage for battery cells in the near time before and after completing previous charging, and performs a voltage balancing process to the identified target battery cell in the next charing operation. The battery cells intended to be processed include: a battery cell of which the cell voltage surpasses an average cell voltage in the near time before and after completing the charging; and a battery cell that marks the maximum cell voltage in the near time before and after completing the charging.