A voltage equalization device of a power storage device provided with battery packs in which a plurality of secondary cells are connected, power converters provided in association with the battery packs, and controllers that control the power converters, and in which the battery packs are connected in parallel via the individual power converters includes a decision portion and a voltage-adjusting portion. The decision portion obtains battery-pack information regarding the states of charge/discharge of the individual battery packs and decides, for each battery pack, whether or not to perform voltage adjustment on the basis of the battery-pack information. When the decision portion decides that the voltage adjustment is to be performed, the voltage-adjusting portion generates offset instructions for adjusting the states of charge/discharge and outputs the offset instructions to the controllers of the power converters associated with the battery packs.