AbstractThe study was conducted between June and September of 2010 in the region of the Dowon Valley of Masan (Mt.), Goseong-gun, Gangwon-do in order to study the region's Beetles and Butterflies. The result of the study showed a total of 66 species of 20 families, and the Staphyrinidae showed the highest species diversity at 20 species (30.3%). The result of the study using FIT method showed a total of 25 species of 10 families in terms of the Coleoptera, and the Tympanophorus sauteri was found to be the dominant species at 767 counts. In terms of other significant values by month, Dominance index was the highest in July at 0.94, while Evenness index and Diversity index were the highest in June, at 0.76 and 1.75 respectively.