PURPOSE: To provide the image forming device where service life of an image carrier and a belt is prolonged and to prevent color deviation at transferring from being generated.

CONSTITUTION: Slack and positional deviation of the photosensitive belt 11 are prevented by providing a direction displacing means displacing the direction of one of a pair of driving rolls 9 and 10 to which the endless belt 11 is in contact with an outer peripheral surface of the image carrier 1 is wound around to be brought close to or separated from the image carrier 1, a driving means to drive the pair of driving rolls 9 and 10 back and forth, bringing the belt 11 into contact with the image carrier 1 when transferring, separating the belt 11 from the image carrier 1 by the direction displacing means when form 22 is switched back and rotating the belt 11 while the belt 11 is pulled by the driving means at the time of transferring and switching back as well.