This study was conducted to prepare systematic and efficient measures for nature conservation and management in Beomseom Island, and to clarify characteristics of distribution of plant resources in southernmost islands of Korean peninsula. The numbers of vascular plants were summarized as 164 taxa included 6 families, 13 genera, and 15 species in pteridophyta, 1 family, 1 genus, and 1 species in coniferophyta, and 59 families, 126 genera, 146 species, and 2 varieties in endospermae composed of 49 families, 97 genera, 114 species, and 1 variety in dicotyledonae and 10 families, 29 genera, 32 species, and 1 variety monocotyledonae. Unrecorded taxa of the flora of Beomseom Island were 19 taxa included 4 taxa of pteridophyta, i.e. Hypolepis punctata, Cyrtomium fortunei, Dryopteris pacifica, and Thelypteris 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 oldhamianum var. roseum, Vitis flexuosa, Clerodendron trichotomum, Elaeagnus glabra, and Siegesbeckia glabrescens. The two rare species, Osmanthus insularis that distributed only Jeju-do and Geomoondo Island and Orostachys iwarenge that distributed only southern parts of Jeju-do in Korea were investigated. The numbers of naturalized plants were 20 families, 33 genera, 34 species, and 1 variety.