An image reader has an original tray for feeding an original from a bundle of originals, a first transport passage for transporting the original fed by the original tray, a scanner for reading an image on one side of the original from one side of the transported original, and a CIS for reading an image on the other side of the original from the opposed side to the one side of the transport passage. To read both sides of an original, the image reader is provided with a mode of reading both sides simultaneously using the scanner and the CIS and a mode of reading both sides of the original only by the scanner with the original reversed using a third transport passage, a fourth transport passage, and a fifth transport passage without using the CIS.