The author colelcted crabs (Tribe Brachyura ) on the coasts of fourteen western islands of South Korea (Paenyong Do, Taechong Do, Sochong Do, Taeyonpyong Do, Kanghwa Do, Yongjong Do, Chagyak Do, Tokchok To. Moktok To. Pukkyoknyolbi Do. Ong Do, ANmyon Do, Pigum Do, and Taehuksan Do) mainly in summers during a period ranging from 1955 to 1962. Of these Islands, Paeknyong , Taehong, Taeyonpyong, Ong, Anmyon, Pigum and Taehuksan Do are the localities where the crabs were investigated firstly by the present author. The collections made by the author consist of 1779 specimens of crabs involving 9 families. 25 genera, 33 species and 5 subspecies (Table2). 23 species of crabs had been reported hitherto from Tokchok To and 7 from Kanghwa Do. In present paper the author adds 1 species to the fauna of crabs of Tokchok To and 7 to that of Kanghwa Do. In present paper the author adds 1 species to the fauna of crabs of Tokchok To and 7 to that of Kanghwa D. Among 38 species or subspecies of crabs collected, Oregonia gracilis, Cancer amphioetus and Chaesmagnathus convexus are new to the fauna of the west coast of Korea. 57 species of crabs are therefore identified in this area. The author collected Pinnotheres cardii on Taechong Do and Scopimera bitympana on Pigum Do. It became, therefore, clear that these two kinds of crabs occur much wider areas than known hitherto in Korea. The nothern limit of the distribution of Ocypoda stinpsoni and Sesarma haematocheir is Kyungki Bay as known already, that of Helice tridens is ,however, more northern part than Kyungki Bay, since they were collected on Paeknyong Do.