PURPOSE: To provide an image forming device forming an image on paper which is capable of being folded in various sizes by a simple operation and also is capable of being filed and arranged.

CONSTITUTION: The image forming device forming image on paper by developing an electrostatic charge latent image formed by exposing the surface of a photoreceptor possesses an image memory 2 storing the information of the image 1 such as read image or the like, a folding position mark memory 4 storing the information of plural folding position marks 3, and an input part 5 selecting a specified folding position mark 3 from the folding position mark memory 4 and a write-in controlling part 7 controlling write-in so as to form the electrostatic charge latent image of the folding position mark 3 with the image 1 on the photoreceptor 6.