The construction of New Seoul International Airport is under way despite much controversy. Among much discussed, but not well-formulated controversy is the possibility of the airport as a hub in the North Asia Region. This paper specifies the factors which render it possible for an airport to be a regional hub. Then each factor is applied to the new airport to see whether it can function as a hub airport. Also examined is the qualitative cost and benefit calculation related to the hub function. The usual discussion has missed one big point of cost side of hub function in the belief that the hub only produces benefits to the national economy where the airline and airport industry belong; earlier-than-expected congestion and the necessity to expand the airport sufficiently enough to accommodate the increasing air demand. An airport as a hub is determined by several factors; geographical location ; economic status of the country where the airport belongs ; bilateral air service agreements according to which the airlines can exercise the route rights; the airport charges which directly influence the cost structure of the carriers ; international aviation and airport related policies of each country in the region ; airport capacity etc. The tentative implications of this paper are the followings; first, the new airport is able to function as a regional hub in the transpacific routes which connect Asian countries and North America. That is, directional hubbing by the airlines is implicated; second, the main benefits may be accrued to american airlines exercising all the route rights in the Asian region; third, the governmental effort to make the new airport a regional hub must take caution in optimizing the hubbing level (% of transitting passengers and freight) between the benefits and the costs. Further Studies may include optimal level of hubbing for the new airport and, quantification of the impact of the new airport on the national economy depending on the degree of hubbing.