A device is allowed to execute a job which is related to calibration work. Inconvenience such that a general job other than the calibration work is erroneously executed by a printer or a copier whose calibration is being executed is prevented. For this purpose, according to the invention, information showing that the calibration of an image forming apparatus is being executed is stored, and a job assigned to the image forming apparatus whose calibration is being executed is assigned to another image forming apparatus.