An apparatus, for a mobile object, that determines a bid-offer condition on an electricity transaction market: acquires information on sell-buy prices for an electricity amount presented by electricity demanders on direct transaction markets, where a contract is executed for electricity that the mobile object directly supplies to or procures from an electricity demander; determines, based on the sell-buy prices, an optimal condition that maximizes a profit from an electricity transaction for the mobile object; and determines, as the bid-offer condition, to place an offer or a bid on an electricity transaction market at a sell or buy price for a to-be-discharged or to-be-charged electricity amount that are determined for each time period in the optimal condition. The sell-buy prices for the electricity amount presented by the electricity demanders on the direct transaction markets are acquired through prediction, or notification from the individual electricity demanders.