An image forming apparatus is provided, which is capable of implementing updating of gamma correction information with a high accuracy while avoiding a wasteful output of a patch image even in the case where environmental fluctuations occur. The image forming apparatus corrects a density tone level of image data by using gamma correction information, forms an image based on the corrected image data, and includes an updating unit configured to update the gamma correction information by using a patch image, and the updating unit updates the gamma correction information by using a patch image the output stability of which is high as first updating and further updates the gamma correction information updated by the first updating by using a patch image the sensitivity of which is high as second updating.