This study is designed to scrutinize South Korea's New Southern Policy (NSP) as middle power diplomacy, which is a new foreign policy that the current Moon Jae-In administration has implemented in order to diversify its diplomacy towards Southeast Asia and India, so as to find out whether the NSP represents successful middle power diplomacy. To this end, the NSP was analyzed by the five characteristics of the foreign policy behavior of middle powers-multilateralism, coalition-building, good international citizenship, niche diplomacy and bridging- as the theoretical criteria of middle power diplomacy. From the analysis, the NSP fulfilled the five characteristics of middle power diplomacy, although there were found some limitations and challenges. Korea utilized multilateralism as a platform to promote the NSP; built coalitions to tackle regional and global challenges through cooperation; exerted good international citizenship by contributing to the common good and interests in the region; employed niche diplomacy in development cooperation in various areas; and played a bridge role by narrowing the development gap in the NSP region. Therefore, this study argues that the NSP represents successful middle power diplomacy and provides some suggestions for the NSP based upon the analysis and implications for Korea's foreign policy as well as the NSP.