A document conveying portion is configured to convey a document sheet along a conveyance path extending sequentially through a turn-around portion at which a conveyance direction is reversed and a predetermined reading position. A reading unit is movable in a predetermined moving direction below the document conveying portion and a document table and includes a unit housing in which a light source, an optical element, and an image sensor are mounted. The reading unit is formed such that, between the turn-around portion and a first end portion of the document conveying portion which is close to the turn-around portion in the moving direction, a second end portion of the unit housing at a side of the first end portion in the moving direction is located in a state where light is applied from the light source to the reading position.