A first profile of each of resources in which information about characteristics of the resources when creating negawatts by controlling operation of the resources and decreasing electric power consumption of the resources or creating posiwatts by increasing the electric power consumption of the resources, and information about contract content between an aggregator and a relevant consumer are described, and a first control scenario for each electric power trading form in which control content of the resources to decrease the electric power consumption is described are stored; a resource group composed of a plurality of resources is generated by combining the resources so that the negawatts or posiwatts which satisfy conditions of a trading target electric power product can be created, on the basis of the first profile of each resource; a control scenario is selected; and each of the resources constituting the generated resource group is controlled accordingly.