Diplopeltula tchesunovi sp. nov., Diplopeltoides holovachovi sp. nov. are described from the Sea of Japan from a depth of 1473 m. D. tchesunovi sp. nov. is characterized by developed cuticular cephalic capsule
underlying amphids, and relatively longer branches of amphids. D. holovachovi sp. nov. is particularly characterized by its small body, cuticle with longitudinal striation, inverted hook-shaped small amphids without sclerotised amphideal plate and dissimilar in shape and size between sexes. Additional data are given on Diplopeltula belgica Vincx and Gourbault, 1992 and Diplopeltoides anatolii Voronov, 1982 found for the first time in deep Sea of Japan. The genera Diplopeltula (fam. Diplopeltidae) and Diplopeltoides (fam. Diplopeltoididae) were recorded in the Sea of Japan for the first time.