Limestone fragments with Late Paleozoic foraminifers were distinguished at Okusukain and Aisaka, north of Himeji, Nishi-Harima district, Hyogo, Japan. They are contained within matrix-supported conglomerate of caldera-originated lacustrine deposits in the Upper Cretaceous Hiromine Formation, which is mostly composed of volcaniclastic rocks. Age distribution of the limestone fragments is variable in comparison with their very rare occurrence. Late Visean, Serpukhovian or early Bashkirian, Moscovian, Wordian and Lopingian ages were attached to the fragments based on their age diagnostic foraminifers, in addition to questionable post-Triassic limestone cobble. All of these limestone fragments are thought to have been derived from the Akiyoshi and Maizuru terranes, and have special paleogeographic and tectonic implications in relation to the nappe tectonics of the Inner Zone of Southwest Japan.