An image forming apparatus forms on a photoconductive body an evaluation chart including first patterns and second patterns. In the first pattern, with respect to a row of dots formed in a main scan direction by a predetermined light beam, a row of dots formed by a next light beam is shifted in the main scan direction, and in the second pattern, with respect to the row of dots formed in the main scan direction by the predetermined light beam, the row of dots formed by the next light beam is shifted in the main scan direction but in a direction opposite to a shift direction of the first pattern. The evaluation chart includes a first pattern group which is formed by the first patterns which are repeated, and a second pattern group which is formed by the second patterns which are repeated.