A printing system which is capable of performing square back processing and preventing occurrence of a new trouble of inadvertently creating a saddle-stitched brochure defective in the appearance of a trimmed edge and/or print appearance, which is unexpected by an operator. A receiving unit receives a job of a first type for creating a saddle-stitched brochure subjected to square back processing and trimming processing or a second type creating a saddle-stitched brochure not subjected to the square back processing but subjected to the trimming processing. A controller controls a trimming position at an end of the sheet bundle for the job and/or an image printing position on a sheet included in the sheet bundle based on whether a job to be processed is of the first type or of the second type.