An image forming apparatus comprises a photoreceptor having an image carrying surface, an exposing device to imagewise expose the image carrying surface to form a latent image, and a developing device to develop the latent image to form a toner image on the image carrying surface, wherein the exposing device is composed of a light source to emit a light beam, a deflector to deflect the light beam so as to form a scanning line with the light beam on the image carrying surface, a cylindrical lens provided between the deflector and the image carrying surface and to focus the light beam on the image carrying surface, and an adjusting mechanism to adjust an inclination of the scanning line and to adjust variance in magnification of an image on the scanning line.