In an SOC compensation method, a first SOC having at least two sections is detected, and a first OCV corresponding to the first SOC is calculated; a second OCV is calculated by using the measured packcurrent and voltage, and an internal resistance, and a second SOC corresponding to the second OCV is calculated; when a difference between the first and second OCVs is greater than a first reference,a first compensation value corresponding to the first SOC among at least two first compensation values corresponding to the two sections is used to compensate the first SOC; and when a difference between the first and second OCVs is less than a second reference, a second compensation value corresponding to the first SOC among at least two second compensation values corresponding to the two sections is used to compensate the first SOC value.