Three unrecorded species, Carex chungii Z. P. Wang, C. tsushimensis (Ohwi) Ohwi, C. multifolia Ohwi were found in Korea. C. chungii Z. P. Wang was found in Is. Wan and Is. Geogeum, Jeollanam-do and Namhae, Gyeongsangnam-do. This species is distinguished from C. leuchoclora Bunge by achenes constricted above in the middle. C. tsushimensis (Ohwi) Ohwi was found in Is. Gageo, Sinan, Jeollanam-do. This species is distinguished from C. conica Boott by pistillate scales with a long arista. C. multifolia Ohwi was found in Haenam, Jeollanam-do. This species is distinguished from C. sachalinensis var. sikokiana (Franch. & Sav.) Ohwi by caespitose and leaf of light gray. We provide here their description, illustration, photographs and the key of related species.