A carriage of an image reading apparatus includes a first lamp and a second lamp. A moving mechanism moves the carriage in a sub-scanning direction from a first side to a second side. The first lamp and the second lamp are arranged in a row in the sub-scanning direction. A control unit turns on any one of the first lamp and the second lamp during reading of one line. The control unit recognizes the position of a first-side edge based on first image data obtained when the first lamp is turned on. The control unit recognizes the position of a second-side edge based on second image data obtained when the second lamp is turned on. The control unit synthesizes the first image data and the second image data to generate job read image data.