POWER STORAGE DEVICE

A power storage device of an embodiment has a power storage element, a table, and a current control unit. A charge characteristic in which any one or more of a first voltage in which charge is started and a second voltage in which charge is started with a maximum current are represented and a discharge characteristic in which any one or more of a third voltage in which discharge is started and a fourth voltage in which discharge is started with a maximum current are represented are defined in sectional ranges of a charging rate in which a charging rate indicating a range of an amount of charge in which the power storage element is capable of storing power is divided into some sections in the table. The current control unit selects a characteristic according to a detected charging rate of the power storage element from the table, sets each voltage of a selected characteristic at a control point of a charge/discharge control characteristic for charging and discharging to/from the power storage element, and performs charge and discharge between a direct-current power supply system and the power storage element through a converter according to a voltage of the direct-current power supply system in accordance with the charge/discharge control characteristic.