Patent ID: 8401429

Claim:
An image forming apparatus comprising: a belt unit including: a driving roller; a driven roller; a driving roller gear which is coaxial with the driving roller; and a belt which is looped around the driving roller and the driven roller; a belt driving gear which is engaged with the driving roller gear to transmit a driving force to the driving roller; a photosensitive drum which is configured to rotate while contacting the belt; and a positioning section which is provided to an apparatus body and includes: a first positioning section configured to contact a portion of the belt unit to position the belt unit in a moving direction of the belt at a position where the photosensitive drum contacts the belt, and a second positioning section configured to support the portion of the belt unit from below, wherein the first positioning section is configured to contact the portion of the belt unit from a direction opposite to a rotating direction of the photosensitive drum at a contacting point with the belt, and wherein the belt driving gear is engaged with the driving roller gear such that a force pressing the belt unit from the belt driving gear via the driving roller gear presses the portion of the belt unit toward both of the first positioning section and the second positioning section.