Based on the distribution, altitude, and OSL age data of the coastal landforms developed in the Sinjido Island of Wando-gun, this study analyzed the shoreline changes and processes of coastal landforms driven by sea level changes during the late Quaternary. The paleo-shoreline was located at 15m a.a.s.l. in the highstand of MIS 7. During this period, the island was divided into two parts on the east and west, and shore platform and beach, which have been changed to marine terrace 2, were formed. The paleo-shoreline was located around 8-10m a.a.s.l. in MIS 5e. In this time, the island was a tie-bar landfom, and beach and nearshore bar were formed, which were changed to marine terrace 1. In MIS 5a, the area became a single island, and alluvial fans were formed in the coast. As coastal sand dunes were formed since 6,000yr B.P., the marine terrace 1 originating from nearshore bar has changed into a buried terrace.