The purpose of this study is to examine the changing process of the collective housing in Korea; focusing on the alteration process of the apartment housing, which became a representative housing type in Korea, nowadays. The alteration process of the apartment housing in Korea can be divided into three stages: the introduction stage, the trial stage and the settled stage. The introduction stage is the period between 1920, when the collective-housing buildings were constructed in Korea for the first time, and the Liberation of Korea(1945). The trial stage is the period between 1945 and 1975. During this period, common housing has been constructed. And the massive apartment buildings were started to be supplied after 1975. The settled stage is the period between 1975 and the present. The main scope of this study will be the introduction and trial stages, since a lot of in-depth studies have been executed on the settled stage. The history of the collective housing of Korea starts with City Housing of Seoul, in 1921. It is guessed that this housing was to be small-sized and row-housing type. The first-built, apartment-type building, in Korea, was Mikuni Apartment House, which was constructed as a boarding room of Mikuni Company. In the introduction stage, apartment buildings were built by Japanese architects, with Japanese housing style. Most of them were planned in dormitory type, and some of them were run as tenant houses. Most of them were constructed by bricks, but sometimes by timbers. Tadami was laid in every room and inside-corridor was located in the middle of the house. Although the major style of the apartment buildings was Japanese, the Korean dwellers of those apartments has been influencing the housing type of them. In the trial stage, apartment housing has been experienced in diverse ways. With the development of building technology, floor heating system was settled in apartment housing. This improved the amenities of apartment dwelling remarkably. Although some heterogeneous characteristics still remained in the apartments of Korea, in terms of housing style, the housing style of apartments has been changed into own style of Korea, in accordance with Korean people's life style. The results of this study give us some good implications regarding contemporary housing plan: First, if the unit size of a collective housing is small, the more space could be available for community activities. Second, when planning of collective housing, more concerns should be payed on surroundings. Third, more attention should be payed about low-rise apartment housing, and more land-friendly planning would be required.