Nishikawatsu, located at Matsue city, Shimane prefecture, is the one of the few historic relics of Yayoi age with weight-style earthenwares (Bundo gata doseihin). In order to clarify the origin of weight-style earthenwares from Nishikawatsu, these samples were investigated by means of EPMA. As a result, it was found that chromite are characteristically recognized in these weight-style earthenwares. From this result studied by this method, it is disclosed that these weight-style earthenwares were probably derived from the northwestern areas of Okayama prefecture and their neighborhood, ultrabasic igneous rock are dominantly distributed and their distribution are restricted to this areas in Chugoku district of southwestern Japan.