An image reading apparatus includes a reading glass, a second guide member, and a control section. The reading glass and the second guide member together form a document feed path. The second guide member includes a white reference plate. The control section performs, when it is determined that shading correction image data is affected by a stain, a stain location determination of whether the stain is attached to the reading glass or the second guide member according to a tone value variation in the portion of the shading correction image data that corresponds to the stain edge, the variation being along a predetermined distance in the main scanning direction.