IMAGE FORMING APPARATUS AND PROGRAM

PROBLEM TO BE SOLVED: To provide an image forming apparatus or the like, which generates less positional shift in each color image.SOLUTION: An image forming apparatus comprises: image forming units for forming images using a plurality of colors; an image output circuit 64 and an image quality adjustment pattern data storage part 65 for allowing each of the image forming units to form two or more successive position control marks in a same color for one pattern used for correcting a positional shift of a formed image; an intermediate transfer belt having the formed position control marks sequentially transferred thereon; a detection sensor part 80 including a light source for outputting light toward the intermediate transfer belt and the position control marks, and a light reception part for receiving reflection light reflected thereon and making it detection signals for detecting the position control marks; and a CPU 61 for specifying by the detection signals a position between the two successive position control marks, and executes a positional shift correction of an image formed by the image forming unit.