An estimation device include: an acquisition unit that acquires information relating to a part of a third characteristic that is an energy storage amount-voltage charge characteristic and/or a fourth characteristic that is an energy storage amount-voltage discharge characteristic, of an energy storage device; a storage unit that stores a plurality of energy storage amount characteristics that are at least any of first characteristics, second characteristics, third characteristics that are energy storage amount-voltage charge characteristics, fourth characteristics that are energy storage amount-voltage discharge characteristics, and pieces of V−dQ/dV in correspondence with a change in a feature value, which is changed by repeated charge-discharge, or stores as a function of the feature value; and a first estimation unit that estimates an internal state of the energy storage device on the basis of the information and the energy storage amount characteristics.