An image forming apparatus includes a first generation unit to determine a density in each of a plurality of regions of a first image formed by the forming unit, and generate first correction data for correcting a density of an image to be formed by the forming unit for each of the plurality of regions based on the density. The first correction unit corrects the density of the image to be formed by the forming unit for each of the plurality of regions based on the first correction data stored by the first storage unit. The second generation unit determines a density of a second image formed by the forming unit, and generate second correction data based on the density. The first determination unit determines an amount of unevenness in the main scanning direction of formation density by the forming unit based on the density determined by the second generation unit. The second determination unit determines that the first correction data is to be generated, based on the amount of unevenness determined by the first determination unit.