Cavernocypris gosuensis n. sp. (Cyprididiae, Cypridopsinae), a new subterranean ostracod species is described with figures of female valves, mouthparts, appendeges and SEM photos from Gosu cave, Danyang-Gun, Chungcheongbuk-Do in Korea. The new stygobiont speices is sixth of the genus Caveroncypris Hartmann, 1964 that characterized by both valeves with a median concave part in ventral view and two groove lines in dorsal view, the reduction of the furca, which is flagellum like in female and the left valve ventrally overlaps the right valve when the carapace is closed and can be distinguished from its congers by left valve with 6 muscle scars in innerpart, mandible palp with one claw and 3 setae on the terminal segment and without seta on the exterodistal border of segment III. The animals were collected within pH 7.31-8.74, temperature ($^{\circ}C$) 13.0-14.6 and dissolved oxygen (mg/l 6.75-14.84 from Aug.2003 to Sep.2004.