Abstract: In a slit exposure scanning type copying machine or the like, a thin white member is fixedly disposed in the image forming main optical path from the vicinity of the end of an original stopping reference member or the vicinity of the end of an original carriage keep member, whereby the image forming main light beam from said vicinity of the end is not effectively transmitted to an image plane but instead, part of an illuminating light beam for illuminating an original from the opposite sides thereof is reflected by the white member, thereby forming predetermined blank spaces at the end portions of copy paper corresponding to the scanning starting end and the scanning terminating end. The white member is disposed at a predetermined angle with respect to the original by taking the scanning direction into account so that the shadow thereof imparted to the slit exposure area on the original surface does not greatly decrease the quantity of light of the illuminating light beam which contributes to image formation.