The fossil foraminiferal assemblage present in Core JZ-01 from central Lake Jinzai, western Japan, was used to document the Holocene paleoenvironment of this area. Wellpreserved foraminiferal fossils are found near the bottom of the core（18.305-19.308 m core depth）along with abundant fossil mollusks, echinoids and ostracods. Ammonia sp.A, Pseudonoion sp.A and Uvigerinella glabra dominate the fossil assemblage-accompanied by Buccella frigida, Ammonia beccarii forma 1 and Nonionella stella. This faunal association is similar to the Jomon-age fauna from the west coast of Lake Shinji. These results indicate that the environment in this location during the early Jomon-era was an enclosed bay with very little evidence for the influence of open marine surface water. This is very similar to Paleo-Shinji Bay at this time.