Carboniferous and Permian limestones, as well as pre-Cretaceous cherts and basaltic volcaniclastic and volcanic rocks, are tectonically intermingled with lower Jurassic to upper Cretaceous siliciclastic rocks in the Yura area, Southern Chichibu Terrane of the western part of Kii Peninsula, Japan. They are seamount originated and highly fossiliferous. Fifty species assignable to 26 genera of Carboniferous foraminifers were distinguished from the limestone blocks in the Yura area (Kaimori, Tatego, and Shirasaki). Among them, 21 species assignable to 11 genera are systematically described, including two new species (Akiyoshiella kaimoriensis and Semistaffella vachardi). Foraminiferal biostratigraphic constraints on the limestone blocks result that the Kaimori block ranges from the middle Bashkirian to Kashirian and the Tatego blocks from the Visean/Serpukhovian to upper Serpukhovian or partly to Bashkirian, while a part of the Shirasaki block, from which the Carboniferous was first distinguished, is lower and middle Kasimovian. Characteristic species are Akiyoshiella kaimoriensis, Profusulinella prisca, and Bradyina nautiliformis in Kaimori; Eostaffella mosquensis and Bradyina sp. A in Tatego; and Protriticites variabilis, Obsoletes burkemensis, and Montiparus matsumotoi in Shirasaki.