Availability of strontium isotope ratios to the provenance studies on ancient ceramics was examined by analyzing roofing tiles and potsherds from five different localities in Japan. The ₈₇Sr/₈₆Sr versus rubidium/strontium diagram gives a better separation of groupings than the rubidium versus strontium diagram does. The strontium isotope ratio is also found to be sensitive enough to differentiate otherwise indiscernible materials fired in a single kiln site. For other analytical studies of roofing tiles and ceramic ware, see AATA 14-1088, 14-1099, 15-1548, 15-1549, and 16-1603.