Disclosed is a method for restoring battery data in a portable appliance. The battery data restoring method includes the steps of receiving reference battery data internally set in a battery and adapted to manage the battery, and storing the received reference battery data as backup data, comparing battery data periodically measured for the battery with the stored reference battery data, and updating the reference battery data set in the battery by the stored reference battery data when it is determined in accordance with the comparison that the measured battery data is damaged. Accordingly, it is possible to make the battery be normally used even when the reference data of the battery is damaged, thereby preventing an abnormal operation of the battery charging system.