When the two same CIS are used for a first image sensor and a second image sensor and they are arranged to face opposite sides of an original document with longer sides (i.e., a main scanning direction) thereof being aligned, if an arrangement order of the array of the imaging elements and the light guiding unit in a document conveying direction is the same, the connectors are located at opposite side ends in a front-rear direction. Thus, an electric cable connected to the connector of the second image sensor is arranged above the second image sensor and extends in a longitudinal direction. Additionally, a horizontal portion of the electric cable is supported on an upper surface of a casing accommodating the second image sensor.