Bacan Island is an island in the administrative region of South Halmahera, North Mollucas Province. One of the biological richness of the region, it is Diorama butterfly. Potential diversity of butterfly in Bacan Island and surrounding areas, requiring require ecologically and molecular studies as a database in the preservation and conservation of the species and its habitat. The purpose of this study is to assess the density and distribution of species of butterfly in Bacan island. This research method is done in several stages, including: a survey to know the various species of butterflies in Bacan island based on morphological characters, sampling (identification and manufacture insectarium), as well as measuring the density and distribution of species of butterflies were observed.