Since 1990, City of Seoul have enforced a policy which encourages a supply of mixed use apartment to solve the problems such as shortage of housing land, urban cavitation and traffic etc. So the city tried to develop easily the mixed use apartment with architectural permit only in commercial district and after 1994, permitted the mixed use apartment to the semi-residential district expanding the residential rate to 90%. It contributed the supply of mixed use apartment to some extent. However this kind of indiscretion supply might raise another urban issues unintentionally at borderland. So we are focusing on the architectural elements of borderland around to analyze a characteristics of urban location to mixed use apartment complex. With the analysis, it especially shows a shortage of infrastructure at small complex which are under 100 units and the small compelex has been intensively developed to the crowded housing area. This is not the original purpose of the city and it might obstruct the complex and urban function. It is very important to support the supply policy of mixed use apartment with proper solutions which can recover the urban and residential function.