PURPOSE: To protect a contact glass from getting dirty by dust and being damaged and to eliminate adverse influence on a formed image by sticking a transparent film which can be comparatively easily peeled off on the surface of the contact glass on the original side.

CONSTITUTION: The contact glass 2 on which the original is placed is arranged on the upper surface of an image forming device main body 1, and the plural transparent films 3 are stuck so as to cover the entire surface of the contact glass 2. The plural transparent films 3 are stuck so that they are easily peeled off from the contact glass 2, and tabs for picking-up are respectively provided in order to make the film 3 more easily peeled off. When the film on a top side, out of the films 3, gets dirty, a user picks up the tab and easily peels it off, so that the new film comes on the top by peeling it off; therefore, a constant quality can be provided without adversely influencing the formed image.