Patent ID: 8515322

Claim:
An image forming apparatus which transfers a toner image to a rotatable endless belt or transfers a toner image to a transfer material carried by a rotatable endless belt, comprising: the rotatable endless belt; guide portions each provided in strips on opposite ends of an inner circumferential surface of the endless belt; a driving roller supporting and rotating the endless belt; a driven roller supporting the endless belt and driven by the rotation of the endless belt; first restriction members each provided on opposite ends of the driven roller in an axial direction of the driven roller, the first restriction members having first contact surfaces which come into contact with the guide portions when the endless belt moves in a belt width direction crossing a rotational direction of the endless belt; and second restriction members each provided on opposite ends of the driving roller in an axial direction of the driving roller, the second restriction members having second contact surfaces which come into contact with the guide portions when the endless belt moves in the belt width direction crossing the rotational direction of the endless belt, wherein the second contact surfaces of the second restriction members are placed nearer to a center in the belt width direction than the first contact surfaces of the first restriction members, and an angle between the first contact surfaces of the first restriction members and the inner circumferential surface in the belt width direction is larger than an angle between the second contact surfaces of the second restriction members and the inner circumferential surface in the belt width direction.