An image forming apparatus includes first and second belt members, at least one color image carrier, a separate image carrier, a primary transfer member, a secondary transfer mechanism, a direct transfer member, a first image detector to detect positional deviation of transferred images from reference pattern images, and a controller to transfer the reference pattern images formed on the at least one color image carrier and the separate image carrier onto the first belt member or onto the second belt member, convey the reference pattern images to the first image detector, cause the first image detector to detect the reference pattern images, and adjust one or more image forming conditions of the image forming apparatus to prevent positional deviation of the transferred images from the reference pattern images based on detection results obtained by the first image detector.