Provided is an image forming apparatus capable of forming a desired image with high accuracy. The image forming apparatus includes: an endless belt configured to convey a sheet; a conveying roller configured to convey the endless belt while being driven by a drive source; a first sensor configured to detect a specific position on the endless belt; a second detecting sensor configured to detect the specific position on the endless belt; a tension roller, which is provided between those sensors, and is configured to support the endless belt in a tensioned state while applying a tensile force to the endless belt; and a control unit.