This study examines the current situation of Korean domestic air market in all aspects and searches the undiscovered problem so far focussing on Jeju-Island area. This study presumes also the improvement scheme of domestic transportation industry by searching the way of decreasing the cost structure which has made many problems. The findings indicate that it is necessary to introduce the types of air planes, fitted for Korean situation, which composes a short air route less than 50kmlh at most to improve the air cost structure in Domestic Aviation Industry. It also needs to make the air-board with a single type of airplane, and to find the maximum of efficiency with the airplane purchase, a labour use and a maintaining cost. This sort of strategies can reduce the cost by changing all seats into the same class, conduction itself a ground-work and using on-line promotion system instead of off-line system in some air-port, and decreasing the seat charge per person. It needs, moreover, minimum ground-work crew and decreasing labour cost, one of indirect cost. These solutions can be more effective when making the local airlines especially for (small) domestic aviation.