An image forming apparatus, forming an image by two-dimensionally fast and slow-scanning and exposing with light that has been modulated in accordance with image data representing an image and visualizing an electrostatic latent image with toner, includes a calculating unit that divides an image region in a fast-scanning direction into plural regions and calculates image data amounts to be used for image formation in the image data per each of the plural regions, and a correcting unit that corrects, on the basis of the calculation result of the calculating unit, unevenness of density in the fast-scanning direction in the toner image resulting from a distance between a position where the toner is supplied to a developing roll and a position where the toner is supplied to each of the plural regions.