In an image reading device, a reading control portion reads image data for one line in a main scanning direction from a first reference member having a reference color. A storage portion stores initial reference data for one line generated based on image data for a plurality of lines read from a second reference member by using an image reading portion while a surface of the second reference member having the reference color is moving in a sub scanning direction perpendicular to the main scanning direction. A reference data generation portion generates reference data based on the image data read by the reading control portion and a high-frequency component of the initial reference data stored in the storage portion. A shading correction portion performs shading correction for image data read from a document by the image reading portion, based on the reference data generated by the reference data generation portion.