An image forming apparatus includes: a developer image carrier movably disposed; a developer image forming device configured to form a developer image; a detector configured to detect a density of the developer image formed on the developer image carrier; a controller configured to control an operation of forming of the developer image by the developer image forming device; an image forming unit configured to control the developer image forming device to form a density detection pattern including the same developer images at at least a first point and a second point with a predetermined distance therebetween; a density detector configured to obtain the density of the first point and the density of the second point of the density detection pattern via the detector; and a calculator configured to calculate a density difference between the first point and the second point based on the densities obtained by the density detector.