An image reading apparatus includes, with the purpose of detecting with improved precision noise generated due to dust on a platen, three line sensors spaced from each other in a sub scanning direction to scan an original in the sub scanning direction, the platen between the original and the three line sensors, a moving mechanism for moving the platen at a rate relative to the line sensors, the rate being different from that of the original relative to the line sensors, an interline corrector synchronizing three data output from the three line sensors to be values of pixels reading a single location on the original, and a noise detector receiving these data synchronized by the interline corrector that are provided successively line by line, and the noise detector includes an isolated noise determiner determining that an isolated point of a chromatic color is a noise pixel.