A new gastrotrich species of the genus Dendrodasys (Dactylopodolidae) is described on the basis of specimens collected from sublittoral fine sandy bottoms at Uljin, East Sea and at Gujwa, the northeastern coast of Jeju Island, South Korea. Dendrodasys duplus is characterized by a triangular head with lateral lobes extending outward, two pairs of pestle organs posterior to the lateral cephalic lobes, a pair of anterior adhesive tubes, the absence of dorsal, lateral and ventral adhesive tubes, large posterior adhesive tubes arising from the anterior third of the caudal peduncle, and paired testes of different lengths. The genus Dendrodasys is recorded for the first time in East Asia.