To provide the method for adjusting the shading correction plate of the image scanning reader which can obtain an image of high quality without variance among image scanning readers irrelevantly to solid-body differences among shading correction plates.

Prior to a read of a shading correction plate, shading correction is made (step S3) and then the shading correction plate is read (step S5) to find adjustment data based upon its measured value as a command (step S6). Then when a desired shading correction plate is read, shading correction is so made that its measured value is the above-mentioned adjustment data set in the image scanning reader, thereby obtaining image information which is not affected by the solid-body difference of the shading correction plate.