An image forming apparatus according to this invention which allows double-sided printing can reduce the toner consumption amount by decreasing the size of a developer image on the second page as compared with the size of a developer image printed on the first page in margin-less printing. To accomplish this, the image forming apparatus includes a setting unit adapted to set, when images are to be formed on both surfaces of a printing material without margin, a size of a developer image on a second page of the printing material smaller than a size of a developer image on a first page of the printing material.