Late Early Carboniferous (late Visean) to late Middle Permian (Capitanian) foraminifers have been recovered from limestone blocks and fragments contained in the Tsunemori Formation in Yamaguchi Prefecture, Southwest Japan, which is unconformably overlain by the Upper Triassic Mine Group. An analysis of the Tsunemori fauna shows an almost identical composition with that of the Akiyoshi Limestone Group. The ages of the limestone clasts of the Tsunemori Formation nearly completely coincide with those of the strata of the Akiyoshi Limestone Group. The Akiyoshi Limestone Group is subdivided into 28 foraminiferal zones, and faunal elements corresponding to 24 of these 28 zones are recognized in limestone blocks and fragments of the Tsunemori Formation. Species from the remaining four zones (late Visean Endothyra sp. Zone, the late Moscovian Fusulinella bocki Zone, early Asselian Sphaeroschwagerina fusiformis Zone, and Bolorian Misellina dyhrenfurthi Zone) in the Akiyoshi Limestone Group have not been found in the Tsunemori Formation, whose blocks and fragments are thought to have been all derived from the ancient Akiyoshi seamount. A limestone conglomerate previously assigned to the basal conglomerate of the Mine Group should be separated from the Mine Group and instead included in the Tsunemori Formation. Twelve species of foraminifers are systematically described.