A study on marine sponges was conducted by SCUBA diving at Ulleungdo Island, Korea, from July 2001 to August 2003. Two species, Mycale (Naviculina) ulleugensis and Mycale (N.) neunggulensis, are new to science. Mycale (N.) ulleugensis n. sp. seems close to M. chungae based on the shape of spicules, but differs in the size of megascleres and sigmas, Mycale (N.) neunggulensis n. sp. seems close to M. flagellifer Vacelet and Vasseur in the type and size of spicules, but differs in the shape of naviculichela. Naviculichela I of M. flagellifer has a spine on the upper part of the felix.