1. An image forming apparatus comprising: a transfer unit that transfers a toner image onto a printing material; a fixing unit that fixes the toner image that was transferred by the transfer unit onto the printing material; a cutting unit that executes cutting processing on the printing material onto which the toner image was fixed by the fixing unit; a determination unit that determines whether adjustment processing is to be executed on the fixing unit, based on a post-cutting size of a first printing material to be cut by the cutting unit and the size of a second printing material on which an image was formed immediately before the first printing material; and an adjustment unit that executes the adjustment processing on the fixing unit if the determination unit has determined that the adjustment processing is to be executed on the fixing unit.