A power control system, configured to exchange electric power with a battery pack, comprising: a power conversion device; and a controller, wherein the battery pack is configured to output a variation of a state-of-charge value among cells to the controller, the variation being determined based on at least one of a detection result from a voltage sensor or a detection result from a current sensor, and the controller is configured to control the power conversion device such that a maximum state-of-charge value among a plurality of the state-of-charge values of the cells is lower than an upper limit of a predetermined state-of-charge range and a minimum state-of-charge value among the state-of-charge values of the cells is higher than a lower limit of the predetermined state-of-charge range, the maximum state-of-charge value and the minimum state-of-charge value being values based on the variation.