Patent ID: 8577266

Claim:
An image forming apparatus comprising: an endless belt that travels circularly by a drive member and has an outer peripheral surface on which an image is formed; a tension applying member around which the endless belt is trained and that applies tension to the endless belt by pressing an inner peripheral surface of the endless belt; a detection member that detects the image formed on the outer peripheral surface of the endless belt, and wherein the detection member is disposed at a position facing the tension applying member; a support member to which the detection member is attached and that movably supports the detection member in accordance with the movement of the tension applying member; a positioning member that positions the detection member with respect to the outer peripheral surface of the endless belt at a portion pressed by the tension applying member; and a holding member at which a shaft section is disposed and that rotatably supports the tension applying member about the shaft section, wherein the support member is rotated in accordance with the movement of the tension applying member, and wherein the holding member rotates about the shaft section so that the tension applying member presses the inner peripheral surface of the endless belt.