PURPOSE: To reverse a transfer paper without decreasing a carrying speed and to make a processing speed higher by forming a spiral path in a sub carrying path and allowing the transfer paper to pass through the spiral path and half-rotate so that one side of the transfer paper may be turned over to the other side.

CONSTITUTION: This device is provided with a main carrying path 13 for carrying the transfer paper P to a transfer position from any of paper feeding trays 11A-11C in order to transfer an image on a photosensitive body 7 to one side of the transfer paper P, and the sub carrying path 14 which receives the transfer paper P where the image is transferred, reverses and fees it to the main carrying path 13 again in order to form the image on the other side. Then, the spiral path 21 is formed in the sub carrying path 14, and the transfer paper P is allowed to pass through the path 21 and half-rotate so that one side thereof may be turned over to the other side. Since the transfer paper P is reversed and the image is formed on the other side without temporary stop, the processing speed is made higher by almost as much as non-stop processing.