The device has an one-dimensional image pick-up (1) which forms image of an original document (14) using a lens (8) and a mirror (7). A light guide prism (2) receives ambient light and adds it to the edge of the image pick-up. Scanning is performed by a photo sensor array (9) in a direction (10) perpendicular to the image pick-up, so as to receive two-dimensional image. A flicker correction unit removes flicker noise of light received from the prism. The flicker signal receiving area and an image signal area are optically isolated completely by the light which radiates from the prism.
