PURPOSE: To wind easily a belt-like photosensitive body to a desired position of a roller by making one end in the width direction of the photosensitive body abut on a positioning member, and executing its positioning.

CONSTITUTION: A positioning member 22 is provided so as to rotate as one body together with a shaft, on the shaft 21 of a roller between a driving roller 1 and a side plate 12 of the rear side. The positioning member 22 consists of a structure having a flange 23 which is suitably larger than the outside diameter of the driving roller 1. Also, a positioning member 25 is provided so as to rotate as one body together with a shaft 24 of a roller between a driven roller 2 of the upper part and the side plate 12 of the rear side. The positioning member 25 consists of a structure having a flange 26 which is suitably larger than the outside diameter of the driven roller 2 of the upper part. Therefore, a photosensitive body 4 is not shifted in the axial direction of the rollers 1W3, and not wound diagonally either.