An automatic document feeder (3) has a front plate (12) located on one of opposite sides of the document feeder in a direction orthogonal to a feeding direction of documents P on a document tray (4), and on the side opposed to an operator. A rear plate (13) is on the other side opposed to the front plate (12). An intermediate transport unit (32) located between the front plate (12) and the rear plate (13) has a frame with an outer wall surface (37) serving as a lower guide surface of document transport path. The front plate (12) has an outer edge (33) at a height equal to or lower than the outer wall surface (37), so as to allow the operator to visually check the document (P) on the outer wall surface (37) from the direction orthogonal to the feeding direction of the documents (P).