An image forming apparatus includes a rotatable belt; a cleaning blade contacted to the belt; image forming stations including a first station and a second station for forming first and second adjustment toner images, respectively, on the belt, the second station being disposed downstreammost position, and the first station being disposed upstream of the second station and downstream of the cleaning blade with respect to a rotational direction of the belt; a detector for detecting the first image and the second image, at a position opposing the belt; a changing portion for changing image forming conditions of the stations on the basis of a result of detection of the detector, a controller for controlling the stations such that in a region between adjacent ones of the same images in a continuous image formations, the second image reaches the blade before the first image reaches the blade.