The philomedid fauna of the East Sea (Sea of Japan) contains nine species, including four species of Philomedes, three of Euphilomedes and two of Scleroconcha. Euphilomedes pseudosordidus new species is described from the southeastern Korean shelf. It is closely related to E. sordidus (Müller 1890) but differs in size and ornamentation of the carapace, number and length of bristles, teeth and claws on the limbs, and structure of the mandible. Comparison is made between these two species. The distribution of philomedids is shown for the East Sea.