An image forming apparatus includes (a) a plurality of image forming unit arranged along a transfer medium, each of which is arranged movable between a lower position and an upper position; (b) an estrangement controller to move each of the image forming units between these positions; (c) a print mode management part to determine a designated print mode; (d) an image forming part to select one or more of the image forming units corresponding to the designated print mode, and to form an image to be transferred to the transfer medium by using the selected image forming units; and (e) a correction process part that performs a correction process. Wherein (f) the correction process part regularly judges whether or not a correction process execution condition is satisfied, and performs a regular correction process when the correction process execution condition is satisfied, and (g) the print mode management part judges whether or not another print process in the designated print mode has been performed after a previous regular correction process, and sets a print mode based on a judgment result by the print mode management part.