A load estimation device measures a voltage and a current supplied to a load connected to a portable power-supply, obtains a feature amount of the load from the voltage and the current. The device obtains a stored feature amount of each of loads, and related load information indicating a plurality of loads which are used in association with each other. The device estimates a load connected to the power-supply on the basis of the obtained feature amount and a stored feature amount, and predicts a load which is not connected to the power-supply and which is a load related to the estimated load on the basis of the related load information.