This paper studies SOC (Social Overhead Capital) of South and North Korea by collecting much literature. Specially, we attempt to analyze the port development strategy after Korea Unification. The lack of data about North Korea makes our study very difficult, so we can only analyze its traffic estimated by the econometric methods. Research results indicate that North Korea`s traffic will be 30 million tons in the optimistic case and 17 million tons in the pessimistic case, in 2011, the time of unification. But, after unification, it is shown that traffic will increase rapidly. So, in 2020, we can find that 260 million tons in the optimistic case and 288million tons in the pessimistic case will be generated separately in north region. Consequently, it is necessary to have to develop 198 berths totally in the North region, especially in Nampo, Najin and Chungjin after unification. Most of all, the direction of port development policy is based on preparation of infrastructure on the Korea peninsula making a role of the central country of a transportation in the Northeast economy region.