An image reading apparatus includes an image reader, an image adjuster and an execution controller that causes the image reader to read an adjustment document and causes the image adjuster to adjust image data generated by the image reader. The adjustment document includes line images and parameter images at positions spaced apart in a main scanning direction in a margin area where the line images are not provided. The parameter images indicate parameters used in image adjustment processing. The execution controller judges whether the image data corresponding to predetermined positions in the main scanning direction coincide, selects one of the image data judged to coincide, and causes the image adjuster to perform the image adjustment using the selected image data and the parameter indicated by the image data generated by reading the parameter image at the position in the main scanning direction of the selected image data.