PURPOSE: To prevent the exposure light from leaking upward directly to protect eyes of the operator, by covering a platen glass with a box-shaped platen cover even in case of the copy for a thick material.

CONSTITUTION: When a thick original B such as a book is copied, a housing 12 is moved upward in accordance with the thickness of the original, but the exposure light is not leaked upward even if a box-shaped platen cover 6 and an upper face cover 2 do not coincide with each other because a side plate 9 and a front plate 8 of the closed box-shaped platen cover 6 correspond to the trapezoidal part of the upper face cover 2. Consequently, in case of not only the copy for a thin original but also the copy for the thick original B, the operator is prevented from seeing directly a light source by the correspondence relation between the trapezoidal part of the upper face cover 2 and the box-shaped platen cover 6 which is supported by the vertically movable housing 12 and cover always the original in the horizontal attitude.