An image reading apparatus enabling a user to place originals on any of sheet feed trays without confirming requested orientation of the originals, either front facing or back facing. Image data of an original fed from a first sheet feed tray and read by a first reading unit is processed handling as image data of a front surface of the original, and image data of an original fed from the first sheet feed tray and read by a second reading unit is processed handling as image data of a back surface thereof. Image data of an original fed from a second sheet feed tray and read by the first reading unit is processed handling as image data of the back surface of the original, and image data of an original fed from the second sheet feed tray and read by the second reading unit is processed handling as image data of the front surface thereof.