An image reading apparatus includes an image data obtaining unit, a foreign material position information obtaining unit, and a separation processor. The image data obtaining unit obtains image data read from a document passing over a read area. The foreign material position information obtaining unit obtains foreign material position information read from the read area in which the document is not present. The separation processor separates the image data into plural objects including a background object, detects, by using the foreign material position information, a streak image portion caused by foreign material in the read area and included in the image data, and assumes a pixel of the streak image portion to belong to the background object if the pixel is present in the background object and has a pixel value equal to or smaller than a threshold determined in accordance with a representative value of the background.