1. An image forming apparatus comprising: a registering device capable of registering a plurality of jobs; an image forming device that forms images corresponding to the jobs registered in the registering device; a discriminating device that discriminates between items for which maintenance is required and items for which maintenance is not required among maintenance items for the apparatus when all the registered jobs are executed; a display device that displays the items for which maintenance is required and the items for which maintenance is not required in different display manners according to the results of discrimination by said discriminating device; and a permitting device that permits start of execution of the registered jobs upon completion of maintenance on the items for which maintenance is required.