Power demand at each base is adjusted so as to improve a renewable energy utilization ratio at all bases. An inter-base workload control system manages an amount of excess power obtained by subtracting a power supply amount of the renewable energy power supply from a power consumption amount associated with execution of a workload in a future time range at the bases, spatial migratable time range information on a spatial migratable time range where spatial migration of migrating the workload in a future time range at the bases to another base is possible and temporal migratable time range information on temporal migration of delaying execution of the workload in the future time range at the bases within the same base and migrating the workload to another time range and a predicted amount of power consumption through execution of the workload in the future time range at the bases.