The Osayama ultramafic body occurs in the high-P/T Sangun metamorphic belt, southwest Japan. The northeastern parts of the Osayama ultramafic body are a serpentinite melange with tectonic blocks of diverse lithology and metamorphic grade. Chemical compositions of the constituent minrals from the tectonic blocks such as kosmochlor-bearing and -free actinolite-tremolite rocks and jadeitites in the Osayama ultramafic body are provided in this paper.