It is high that occupancy rate of apartment house in Korea, spite of short history of the using multiple dwelling house. So that, trouble and dispute occurs often on right or responsibility, liability and obligation about ownership, Utilization, maintenance. Especially in renovation project, the project progress held up in perception gap or conflict of interest with residents. These dispute in daily life and delay of project occurs ambiguous borderline or distinction of Common Used(Sharing) Parts) and Exclusive Possessed (Private) Parts. The law now in force is considered in this paper about theses item. Summarizing the conclusion is as below. 1) In the law now in force the literal meaning of a word, Exclusive Possessed (Private) Parts is expressed with concept of Ownership, But Common Used (Sharing) Parts is described with Utilization concept. But in calculation of floor area, complementary set of Private Parts is Sharing Parts. This is contradiction in logic and linguistic. 2) Although above, calculation base of Private Parts is inner line of exterior wall. This is unjustly defined. 3) Especially about balcony (in correct architectural vocabulary is veranda) subordinate law contradictits superordinate law. And in structural mechanics also, minute prescription is necessary about Private Parts and Sharing Parts.