Patellogastropods are poorly recorded in sedimentary rocks. This hinders our understanding of their evolutionary and migratory history in the geologic past. The Middle Pleistocene Ichijiku Formation in the Boso Peninsula, central Japan, consists of sand wave deposits formed at 50 to 130 m water depth by unidirectional currents on a sea floor and contains an unusually well preserved and highly diverse patellogastropod assemblage. A total of 12 patellogastropod taxa have been collected: seven species of Cellana (Nacellidae), four species referred to as living Lotiidae, and one undetermined species of the family Lottiidae. Of the seven species of Cellana, five are described as new (Cellana yamamotoi sp. nov., C. bosoensis sp. nov., C. igniculus sp. nov., C. kobayashii sp. nov., and C. kamatakiensis sp. nov.), one is related to the modern C. toreuma (Reeve), and one poorly preserved taxon is unnamed but probably extinct. The assemblage represents a window into a Middle Pleistocene patellogastropod community in central Japan, which differs markedly from the modern fauna in the dominance of the genus Cellana. Selective extinction is noted for the genus Cellana. The habitat loss during the glacial lowstands of sea level is a plausible explanation for this selective extinction.