In the present report, the writer describes the foraminiferal faunas from the Miocene formations of the Miyoshi, Shôbara, Niimi, Tsuyama and Nara basins distributed in the western Setouchi Province, Japan, and discusses the relation between two units: microbiostratigraphical ones based on the foraminiferal assemblages of the faunas, and lithostratigraphical ones, previously established, of the Miocene marine sediments in the basins.