This paper examines the thinking and movements of south and north Korea on Dangun. Dangun-nationalism means the consciousness or movements which persued the ethnical integration under the identity of Dangun’s decendants. It thought that Korean nation had one origin which began with Dangun’s founding Joseon in B.C.2333. Dangun-nationalism had worked as a power source for the national identity, independency, integration, democracy, justice and welfare. After the partition of the Korean peninsula, South Korea invited the Dangun nationalism and adopted it positively as a national integration equitment. But as time went on Dangun nationalism was stagnated, because the anti-Dangun nationalism powers were gradually growing. From the early days of founding state North Korean government made many afforts to inquire the history of Dangun’s Old Josun, but he rejected the Dangun nationalism because he thought Dangun nationalism was the bourgeois ideology. But in 1993, North Korea’s Social Science Academy announced the Excavation Report of the Dangun’s Tomb and insisted that Dangun was an existed person and all Koreans are Dangun’s decendents. But in North Korea class-centered world view is working until now, and so North Korea’s Dangun Nationalism is defferent from that of traditional age. Dangun nationalism is in a forked road today. Dangun nationalism must be resuscitated for the South-North unification of Korea and the idea of Global-wide Korean community. The intellectual society and South & North Korean government must endeavor to revive the Dangun nationalism.