Geology and stromatolite fossil localities of Socheong Island are reviewed on the basis of previous studies and recent field survey. A new fossil locality of stromatolites which are very well preserved is recognized in Bunam area, northeast of Socheong Island. An outcrop composed of sandstone and shale alternations which exhibit well-developed laminations and folds is also found in the east of the Socheong harbor, and it is regarded as one of the symbolic features of the geology in Socheong Island. Stromatolite fossil localities of Socheong Island contains diverse and well-preserved Late Proterozoic stromatolites which are correlated with those from the Mukchon and Myoraksan series of the Sangwon System and diverse sedimentary structures such as ripple marks, desiccation cracks, and raindrop imprints. Stromatolites of Socheong Island, the oldest fossil Natural Monument of Korea, should be preserved at the national level, and continued intensive research must be conducted.