An image reading apparatus includes: three line sensors mutually spaced in a sub scanning direction; a platen arranged between the original and the three line sensors; a mover moving the platen at a rate relative to the three line sensors, the rate being different from that of the original relative to the three line sensors; a first detector detecting a noise pixel based on a plurality of data output from the three line sensors; and a second detector detecting a subsequent noise pixel based on the noise pixel detected with the first detector.