PURPOSE: To provide a means for eliminating such a drawback that a paper guiding member arranged in a pair of returning rollers in a paper reversing device for an image forming device can not accurately carry a paper which is stiff when the paper is reversed and transferred by a pair of returning rollers.

CONSTITUTION: A paper guiding member 19A in the paper reversing device is provided with a switching control means 23 by which the member 19A is projected to a paper carrying side further than the surface of a driving roller 4 which contacts with a paper so as to separate the paper from the surface of the rotating driving roller in the case of carrying in the paper and it is retreated from the abutting position of a pair of returning rollers consisting of the driving roller 4 and a contacting and separating driven roller 5 in the case of carrying out the paper, so that constant carrying force is always given even when the stiff paper such as a cardboard is used.