An electric power trade brokering system includes: a task information acquiring unit that acquires 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 determines, 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.