An image reading apparatus includes a light source device, a reader, a plurality of strip-shaped density reference members, and a shading corrector. The plurality of strip-shaped density reference members that extend along main scanning direction. The plurality of strip-shaped density reference members are separately disposed in at least three positions including an upstream end portion, a center portion, and a downstream end portion in the moving direction of the sub scanning direction within a readable area of the reader. The shading corrector is configured to calculate shading correction data using density distribution data obtained by reading the plurality of strip-shaped density reference members with the reader and correct image data of the printed document on a pixel to pixel basis, based on the shading correction data.