In order to illustrate the flora of vascular plants distributed in the Five West Sea Islands, the authors collected vascular plants intensively in Baengnyeongdo and Socheongdo from May 2015 to August 2015. Also, voucher specimens from the previous investigations (Daecheongdo, Yeonpyeongdo and Soyeonpyeongdo) deposited at the Korean National Arboretum (KH) were re-identified. All of them were comprised of 108 families, 420 genera, 728 species, 6 subspecies, 86 varieties and 14 forms, totally 834 taxa. There were 8 endemic taxa, 19 rare taxa, 27 taxa for floristically specific to Korean floral zone except the species of their 1st and 2nd degree, and 107 naturalized taxa among the collected plants. Owing to their unusual phytogeography and low number of populations, the taxa Rosa maximowicziana Regel, Allium anisopodium Ledeb., Bistorta pacifica (Petrov ex Kom.) Kom., Scorzonera austriaca subsp. glabra (Rupr.) Lipsch. & Krasch. ex Lipsch., Iris dichotoma Pall., Amsonia elliptica (Thunb.) Roem. & Schult. were considered the most important. Based on these results, it is clear that appropriate plants to conserve the natural habitat of the Five West Sea Islands must be made immediately.