An automatic original feeding device includes an original paper feed tray that loads an original to read the image, the original paper feed tray being supported on an upper face of a platen glass for an image reader that reads an image of the original passing through an original reading position set along a straight line on the upper face of the platen glass disposed at an upper end; an original paper output tray, original feeding members feeding sequentially the original laid on the original paper feed tray to the original reading position and the original paper output tray and a strip sheet attaching part attaching detachably a strip colored sheet, the strip sheet attaching part provided in a back platen member disposed in a portion opposed to the original reading position under the condition that the sheet attaching part is supported on the upper face of the platen glass.