To provide an image forming device capable of driving a transfer roller, without using a gear.

The transfer roller 3 is provided in press-contact with an image carrier 2. A pair of positioning members 7 are provided to be coaxial with the transfer roller 3. The rotary drive of the transfer roller 3 is attained in such a manner that the transfer roll 3 in contact with the image carrier 2 and the positioning members 7 are rotated with the rotation, when the image carrier 2 is rotated. Thus, the gear is not used, thereby the cost is reduced and a failure in carrying a transfer material due to the failure with time in the engagement of the gear can be prevented. Further, not only irregularities in carrying caused by the backlash and the generation of a noise caused by the engagement do not occur because the gear is not used, but also the positioning members 7 are worn together with the transfer roller 3. Thus, a change over aging in the gap or encroaching quantity between the image carrier and the transfer roller 3 is small and the following effect is obtained; the fact that a difference in linear velocity is hardly made as well.