To survey the appearance pattern of ants in Mt. Chiaksan, 1,358 colonies 0f ant species were collected in three courses for two years (2009~2010). As the result, the ant fauna of Mt. Chiaksan were found to be 57 species belonging to 27 genera under 6 subfamilies. Among them, 15 species were newly recorded to inhabit in Mt. Chiaksan: Pachycondyla chinensis, P. pilosior, Hypoponera gleadowi, Proceratium itoi, Myrmica kotokui, M. kurokii, Stenamma ussuriensis, Leptothorax acervorum, Monomorium chinense, Mo. intrudens, Crematogaster vagulla, Camponotus vitiosus, Formica sanguinea, F. yessensis, and Lasius umbratus. Consequently a total of 60 species under 27 genera of Formicidae are recorded from Mt. Chiaksan.