Abstract: An image forming apparatus includes a photosensitive belt carried by a driver device, for forming a toner image thereon; an internal transcription belt for transcribing the toner image; and a transcription portion for transcribing the toner image, which is transcribed on the internal transcription belt, onto a recording medium. A transcription side roller is suspended with the internal transcription belt thereon, and disposed on a side of a photosensitive belt side roller. Detectors detect a first cycle of the internal transcription belt, and a second cycle, which starts measurement delaying by ½ cycle of the photosensitive belt side roller from the first cycle measurement start. A controller conducts speed compensation of the photosensitive belt by referring to the first cycle and the second cycle, wherein the internal transcription belt is in contact with the photosensitive belt, so that it is carried following thereafter.