1. An image forming apparatus comprising: a movable first image bearing member on which a toner image is formed; and a movable second image bearing member having a contact part in contact with said first image bearing member, to which the toner image on said first image bearing member is transferred, wherein the toner image on said second image bearing member is transferred onto a transferring material, wherein a dot-shaped dot image formed of a toner different from the toner image is formable on said first image bearing member, and wherein the dot image is variable according to a condition upon forming the toner image on said transferring material.