One embodiment of the present invention is provided with an image information storage unit, an image information processing unit, an actual image forming unit, an image information control unit that controls transfer of image information between each of the units, a power supply control unit, a cost information management unit that holds basic cost information prescribing power costs dependent on a usage time and calculates unit cost information, and an image processing time management unit that calculates a processing time required for image output jobs, wherein the image information control unit sets the execution timings of the image output jobs based on the basic cost information so that a total of image output costs of the image output jobs stored in the image information storage unit is lowest.