An image forming apparatus capable of preventing a job from being forcibly terminated when it is unnecessary to remove a removable unit, and thereby reducing downtime. The image forming apparatus is provided with a drawer unit as a movable unit, which can be drawn out from the apparatus, and a lock unit that can be switched between a locking state in which the drawer unit is inhibited from being drawn out and an unlocking state in which the drawer unit is allowed to be drawn out. When a jam occurs at a position outside a predetermined range in which it is necessary to draw out the drawer unit to perform jam processing, the job interrupted due to the jam is resumed after completion of jam processing without forcibly terminating the job even when the unlocking state of the lock unit is not detected.