In Japan 14 species in 21 genera of Carboniferous trilobites were known in 1980 and 22 species in 11 genera of the Permian ones in 1984. Adding a few species described since then, the Permo-Carboniferous trilobites of Japan total about 70 species at present. They are described from 18 horizons, namely 11 and 7 horizons respectively for the Carboniferous and Permian ones. They are compared with the faunas of the Mongolian geosyncline, Hwangho and Yangtze basins and Southeast Asia. While the Mongolian sea retreated from the west side through the periods, the route of migration was maintained toward the Mediterranean sea through the Himalayan geosyncline until the end of the Palaeozoic era. Some trilobites of Japan reveal relationship further toward the Australian and North American sides.