To provide an image forming apparatus that can properly instruct post processing with respect to a sheet bundle without impairing final appearance of a printed matter, and to provide a method and program for instructing post-processing.

The image forming apparatus for producing a sheet bundle prints a print image on a plurality of sheets based on a print job and executes post-processing by a post processing device to finish the sheets as a printed matter. The image forming apparatus includes a post processing instructing unit that, when generating a print image, executes predetermined post-processing (trimming and binding) specified based on the print job to impart instruction information related to a specific post-processing in a predetermined region (fragment to be cut by trimming and end surface to be attached with a cover in binding) of a sheet bundle.