In a frame (8) holding a sensor board (7) with a plurality of photoelectric conversion elements (6k) arranged and mounted and an imaging element (5) for focusing light reflected from an original onto the sensor board (7), the imaging element (5) includes a plurality of rod lens arrays (5) each having at least one cut end in a lengthwise direction, and cut portions of the rod lens arrays (5) are connected to each other to be tailored to a predetermined reading width, the frame (8) includes a holding section (13) for holding the rod lens arrays (5), and the holding section (13) includes a bottom surface (13B) widened at a part where a cut portion and/or a connection portion of the rod lens arrays (5) is located.