An electric power trade brokering system comprising: a task information acquiring unit that is configured to acquire task information about a plurality of tasks of a moving body on which a storage battery is mounted and that is movable by utilizing electric power provided from the storage battery; and a trade counterparty determining unit that is configured to determine, based on the task information acquired by the task information acquiring unit, a counterparty to trade electric power with the moving body at a position where at least one task among the plurality of tasks is carried out, wherein the task information includes information about a position and time at which each among the plurality of tasks of the moving body is carried out, and wherein the trade counterparty determining unit has: an extraction condition determining unit that is configured to determine, based on the task information, a period in which the moving body can trade electric power, for at least one task among the plurality of tasks and at a position where the at least one task is carried out; an extracting unit that is configured to extract, from a plurality of preregistered candidates, one or more candidates that can trade electric power with the moving body, in the period determined by the extraction condition determining unit, at the position where the at least one task is carried out; and a trade schedule determining unit that is configured to determine a position, period and counterparty of one or more electric power trades based on information about one or more candidates extracted by the extracting unit. a task information acquiring unit that is configured to acquire task information about a plurality of tasks of a moving body on which a storage battery is mounted and that is movable by utilizing electric power provided from the storage battery; and a trade counterparty determining unit that is configured to determine, based on the task information acquired by the task information acquiring unit, a counterparty to trade electric power with the moving body at a position where at least one task among the plurality of tasks is carried out, wherein the task information includes information about a position and time at which each among the plurality of tasks of the moving body is carried out, and wherein the trade counterparty determining unit has: an extraction condition determining unit that is configured to determine, based on the task information, a period in which the moving body can trade electric power, for at least one task among the plurality of tasks and at a position where the at least one task is carried out; an extracting unit that is configured to extract, from a plurality of preregistered candidates, one or more candidates that can trade electric power with the moving body, in the period determined by the extraction condition determining unit, at the position where the at least one task is carried out; and a trade schedule determining unit that is configured to determine a position, period and counterparty of one or more electric power trades based on information about one or more candidates extracted by the extracting unit. an extraction condition determining unit that is configured to determine, based on the task information, a period in which the moving body can trade electric power, for at least one task among the plurality of tasks and at a position where the at least one task is carried out; an extracting unit that is configured to extract, from a plurality of preregistered candidates, one or more candidates that can trade electric power with the moving body, in the period determined by the extraction condition determining unit, at the position where the at least one task is carried out; and a trade schedule determining unit that is configured to determine a position, period and counterparty of one or more electric power trades based on information about one or more candidates extracted by the extracting unit.