An image reading apparatus is adapted to nip a sheet having an image formed thereon with a main roller and conveying rollers, the conveying rollers being in contact with this main roller, to convey the sheet along the main roller to a reading line opposed to a lowermost point of the main roller, and to read the image with an image sensor for reading an image, and includes reading white background plates which press the sheet against the reading line on both sides of the main roller.