An image forming apparatus configured to carry out development using a light toner and a dark toner having substantially the same hue, includes a pattern forming unit configured to form a pattern using a dark toner and a light toner, a pattern reading unit configured to read the density of the pattern formed on a sheet of recording paper after the pattern has been fixed, and a gradation correction unit configured to correct the gradation characteristics of image data for the light toner by changing the slope of the gradation characteristics with zero level as a base point. The changing of the slope is based on the density characteristics of the pattern read by the pattern reading unit and the ratio of the amounts of the light toner and the dark toner that have been used.