A state of charge (SOC) compensation method of a battery and a battery management system using the same. A charge/discharge current of the battery is used for calculating the SOC and an SOC voltage that is a value in an OCV table, a rheobasic voltage is calculated, an error in the SOC is measured by using a difference between the SOC voltage and the rheobasic voltage, and a range of the error is determined among multiple effective ranges. Subsequently, the SOC is compensated by using a compensation SOC set in correspondence with a range in which the error is included to thereby measure a more accurate SOC of the battery.