Recent high-performance sports shoes sometimes have a sole which made from several materials composed of diŠerent properties. One of such material is foaming rubber. This is produced by foaming a rubber, cut with a mold, then pasted to a sole. As this foaming rubber-contained sole causes conspicuous diŠerences in a process of manufacturing, there is no identical sole even if the shoe is of the same size. This intrinsic distinction could be extremely eŠective in diŠerentiating diversities.