An image forming apparatus having a photoconductive drum to form an electrostatic latent image corresponding to a predetermined image by a laser beam scanned after being electrified to a predetermined electric potential, and a developing roller to rotate together with the photoconductive drum having a developing gap therebetween and to transfer a developer, which is a mixture of a toner and a carrier, to the photoconductive drum to form a toner image on the electrostatic latent image, wherein a linear velocity ratio of a linear velocity of the developing roller to a linear velocity of the photoconductive drum is provided at a predetermined ratio, which provides maximum quality of the toner image.