This study was conducted to prepare systematic and efficient measures for natureconservation and management in Beomseom Island, and to clarify characteristics ofdistribution of plant resources in southernmost islands of Korean peninsula. The numbers ofvascular plants were summarized as 164 taxa included 6 families, 13 genera, and 15 speciesin pteridophyta, 1 family, 1 genus, and 1 species in coniferophyta, and 59 families, 126genera, 146 species, and 2 varieties in endospermae composed of 49 families, 97 genera, 114species, and 1 variety in dicotyledonae and 10 families, 29 genera, 32 species, and 1 varietymonocotyledonae. Unrecorded taxa of the flora of Beomseom Island were 19 taxa included4 taxa of pteridophyta, i.e. Hypolepis punctata, Cyrtomium fortunei, Dryopteris pacifica,andThelypteris granduligera, 6 taxa of monocotyledonae, i.e. Setaria viridis, Zizania latifolia,Scirpus triangulatus, Zantedeschia aethiopica, Spirodela polyrhiza,and Dioscorea nipponica,and 9 taxa of dicotyledonae, i.e. Alnus firma, Boehmeria platanifolia, Aconogonum ajanense,Phytolacca americana, Melandryum oldhamianumvar. roseum, Vitis flexuosa, Clerodendrontrichotomum, Elaeagnus glabra, and Siegesbeckia glabrescens.The two rare species,Osmanthus insularisthat distributed only Jeju-do and Geomoondo Island and Orostachysiwarengethat distributed only southern parts of Jeju-do in Korea were investigated. Thenumbers of naturalized plants were 20 families, 33 genera, 34 species, and 1 variety.