Provided is an image reading apparatus including a light source that irradiates an original document that passes through a reading position with light, a light receiving unit that receives reflected light from the original document, a background member that is inclined at an angle where a difference between an incident angle of the light from the light source and a reflection angle of the light to the light receiving unit is smaller than a difference therebetween on the original document present at the reading position, with the original document at the reading position interposed between the background member and the light source, and a foreign substance detecting section that detects, when the original document is not present at the reading position, a foreign substance present at the reading position.