The study deals with composition of maiofauna communities on shells of the Japanese scallop Mizuhopecten yessoensis in cages' overgrowths in Kitovy Bight and near the Reineke Island (Peter the Great Bay, Sea of Japan). It was found that meiofauna of cages' overgrowths was represented by 11 taxonomic groups of animals (class, order). Eumeiofauna included the groups Foraminifera, Nematoda, Halacarida, Harpacticoida, Turbellaria, and Ostracoda. Pseudomeiofauna was represented by Polychaeta, Pantopoda, Bivalvia, Gastropoda, and Amphipoda fry. Nematoda were the dominant group (from 7 to 40 %). Thirty-three species were identified. Four nematode species, Anticoma possjetica, Axonolaimus seticaudatus, Monoposthia latiannulata и Pseudoncholaimus mediocaudatus, were mass species; they were recorded at all depths and in all exposure periods. Predominating trophic groups were omnivorous and predators (37 %) and «scrapers» (33 %).