The ratio of old persons among the total population is rapidly increasing and the apartment has become to the representative housing type in Korea. This means that many old persons would live in multi-family houses. Therefore the study was intended to examine the preferred characteristics of interior space organization in multi-family house by the aged. The characteristics were the number and usage of bedroom, necessity and type of dress room, type of living room, arrangement of work centers in kitchen, LDK type, the number and layout of bathroom, and type of entrance and balcony. The subjects were 122 old persons who lived in multi-family houses in Ulsan. The individual interview was carried out for collecting the data. The results were as the followings; The characteristics of interior space organization in multi-family houses preferred by the elderly were three bedroom, two bathroom, DK or LDK type, open planned living room, L shape arrangement of kitchen work center, entrance connected directly to outdoor space such as elevator hall or corridor, and the balcony located in front of living room and at the back of small bedroom. Even thouth the average age of population has increased, many apartments still be planned and provided without consideration of old persons. This study would contribute to plan the multi-family houses for the elderly.