1. An image forming apparatus comprising: a job storage device that stores a job input by a user; an adjustment item-detecting device that detects items of mechanical adjustment for the apparatus from contents of at least one job stored in the job storage device; a display device that displays an adjustment table describing the items of mechanical adjustment detected by said adjustment item-detecting device; an adjustment item-selecting device that allows the user to select an item of mechanical adjustment on which adjustment should be executed, from the items of mechanical adjustment described in the adjustment table displayed on said display device; and an adjustment executing device that executes adjustment on the item of mechanical adjustment selected by the user using said adjustment item-selecting device before the execution of a job is started.