In the discharge section to correct the potential of toner image on the intermediate transfer body before the secondary image transfer and to obtain a good secondary transfer image, it is made that the opposite electrode is brought into contact with the back surface of the intermediate transfer body under the stable condition. Between the primary image transfer unit and the secondary image transfer unit along the intermediate transfer body, the scorotron discharger is arranged at the position where the intermediate transfer belt is supported plane-likely, and on the rear side of the intermediate transfer body opposing to the grid of the discharger, the opposite electrode composed of the electric conductive brush is arranged, the electric conductive brush is brought into contact with the intermediate transfer body, and electrically grounded, and at least one of the plurality of support members has a configuration for adding more tension in the vicinity of the center of the intermediate transfer belt than in the vicinity of the both ends.