Battery management system and driving method thereof

A battery management system for effectively and accurately estimating a state of charge (SOC) of a battery is disclosed. In one aspect, the battery management system includes a main controller unit (300) configured to receive current and voltage data from a sensing unit (200) and calculate an open circuit voltage (OCV) upon determining that a sum of integrated current values exceeds a predetermined value. The battery management system is further configured to estimate the SOC based on the calculated OCV.