When executing an image forming process for same sheets divisionally a plurality of number of times, a subsequent image forming process needs to be prevented from becoming impossible depending on the process result of a preceding image forming process. To accomplish this, when executing a second image forming process for a sheet having an image formed by a first image forming process is designated, an image forming apparatus of this invention restricts execution of post-processing for the sheet that has undergone the first image forming process even when executing the post-processing for the sheet is designated.