PURPOSE: To provide an image forming device for transferring, onto a transfer material, an image developed from an electrostatic latent image formed on the outer circumferential surface of an image carrier rotating in a prescribed direction, which never cause a vibration or uneven rotation in the image carrier while a rotating force is transmitted from a rotating force supplying source to the image carrier, thereby never causing a shaking of profile on the image transferred onto the transfer material, and consequently never causing a convergence error when a process color printing image is formed on the transfer material.

CONSTITUTION: An image forming device has driving pulleys 70BK, C, M, Y to which rotating forces are supplied from motors 68a, 68b; driven pulleys 62BK, C, M, Y integrally rotated with photoreceptor drums 12BK, C, M, Y; and a flat belt 76 laid between the driving pulley 70 and the driven pulley 62 to transmit the rotating force from the driving pulley 70 to the driven pulley 62, and the flat belt 76 is an endless belt formed from a highly rigid material.