Image forming apparatus

An image forming apparatus comprising:

• a plurality of image forming portions which form toner images of different colors;
• an intermediate transfer belt
• which is an endless belt wound around a drive roller and a driven roller,
• which is arranged along the plurality of image forming portions, and
• onto which the toner images respectively formed by the plurality of image forming portions are primarily transferred to be sequentially superimposed one on another;
• a belt displacement detector which detects displacement of the intermediate transfer belt in a rotation axis direction of the driven roller;
• an attraction force changer which is operable to change electrostatic attraction force of the driven roller with respect to the intermediate transfer belt exerted on each of opposite end sides of the driven roller in the rotation axis direction thereof;
• and
• a controller which controls operation of the attraction force changer,
• wherein,
• when the belt displacement detector detects the displacement of the intermediate transfer belt, the controller makes the attraction force changer increase the electrostatic attraction force of the driven roller with respect to the intermediate transfer belt exerted on a side of the driven roller opposite to a side toward which the displacement has taken place.