Molluscan shell remains collected by a Smith-McIntyre grab sumpler with bottom sediments of Lagoon Saroma, Hokkaido, were examined. Shells are widely distributed in the lagoon, especially along the inner side of the sand bar. The molluscan shells examined are identified to 24 genera and 28 species of bivaves, and 15 genera and 16 species of gastropods. The fauna is composed of epifauna and infauna on or in sand and mud bottoms. Half of the species are cold current elements and most of the other half are warm-temperate ones.