According to an example embodiment of the present disclosure, a power storage module state estimation apparatus comprises a parameter calculator configured to calculate a parameter based on a current value of a power storage module, wherein the parameter includes at least one of a direction having a high frequency of current flowing in the power storage module, an average current value of the power storage module, and a charge and discharge capacity after the direction having the high frequency of current flowing in the power storage module is switched; and a hysteresis compensator configured to use the parameter to compensate an open circuit voltage of the power storage module.