According to one embodiment, an evaluation device for an energy storage device includes first processing circuitry and second processing circuitry. The first processing circuitry acquires data items including an amount of charge and a voltage value measured in a measurement period from the energy storage device, the energy storage device being charge-discharge-controlled according to charge-discharge command values. The second processing circuitry generates a representative data item of voltage values for amounts of charge, based on the data items acquired for the measurement period; and evaluates a degradation state of the energy storage device, based on a relative change between a plurality of the representative data items corresponding to a plurality of the measurement periods.