An image forming apparatus has a memory, an image forming unit, an intermediate transfer member, a density detector, a background density measurer, a test patch controlling unit and a density correcting unit. The density detector detects the density of the intermediate transfer member. The background density measurer stores background density, in the memory in correspondence with position information on the intermediate transfer member at a predetermined timing before a calibration for adjusting image formation density. The test patch controlling unit causes the image forming unit to form a test patch, on the intermediate transfer member while the intermediate transfer member is driven at a predetermined speed. The density correcting unit executes the calibration to adjust image formation density according to a difference between the background density stored in the memory when executing the calibration and corresponding to the position and density of the test patch.