To provide a grading system designed to reduce labor in originating data for making pattern pieces of same shape differing in size from one another based on master size.

For respective constitutive points in each size, their coordinates and kinds are stored in advance, and whether these constitutive points lie midway on a curve is judged (S801), and if not, the data for obtaining the constitutive points of a pattern piece of the same shape differing in size from the master size are automaticelly computed (S710, S711); in contrast, if yes, such data are made inputtable manually.