An image processing apparatus has an original mount, a recording material mount for mounting recording materials, a supply roller, a separating unit, a reading unit for reading an image of the original, an original detection sensor for detecting the original on the original mount, and an original widthwise direction reference surface for being abutted by the original mounted on the original mount to position that original. The recording material widthwise direction reference surface is used to position the recording material so that a portion of the original does not superpose on the recording material having a maximum width and the original detection sensor detects that a portion of the original mounted on the original mount is not superposed on the recording material having maximum width.