TRANSFER UNIT AND IMAGE FORMING DEVICE HAVING THE SAME

PROBLEM TO BE SOLVED: To provide a transfer unit capable of preventing fluctuations in rotation speed of a driving motor for driving a driving roller of an endless belt and a photoreceptor drum, and an image forming device having the same.SOLUTION: In an intermediate transfer unit 15, the circumference of a first tension roller 14 is formed to be same as the circumference of a secondary transfer backup roller 12. The first tension roller 14 is assembled so as to make the maximum radius portion Srmax on an outer peripheral surface 14c of the first tension roller 14 oppose to a circumferential direction center portion Kc in a range K contacting with the outer peripheral surface 14c in the intermediate transfer belt 8, when the maximum radius portion Drmax on an outer peripheral surface 12c of the secondary transfer backup roller 12 opposes to a circumferential direction center portion Jc in a range J contacting with the outer peripheral surface 12c.