The fish fauna of Munsom in Jeju-do, Korea, was investigated for a total of five times underwater from April 2009 to October 2010. Fish specimens were collected with a small net by SCUBA diving and fish specimens difficult to collect were photographed underwater using a underwater camera and a camcorder. The fish specimens collected from the sea around Munsom were identified as 91 species, belonging to 73 genera, 39 families, and 11 orders. Among them, the largest group was Order Perciformes, comprising 54 species and 21 families, consisting 59.3% in total number of species and the following 19 species of Order Scorpaeniformes was 20.8%. In this study Amblyeleotris sp. of family Gobiidae was discovered as new species by underwater photography in Korea. It was more the demersal fishes (55%) than the pelagic fishes (45%) and in social behavior pattern it was much more species swimming alone than schooling.