This study aims at the suggestion of possibility that a housing density will maintain properly and that an ecological hill housing will recover a rapport with the ground. That is, both residential planning on the hillside and ecological architecture as a concept for development are chosen for study category, and relationship between the hillside and the hill housing is theorized and then propriety is analysed through application of the ecological planning elements. The results of this study are as follows: 1. Now that the hillside is regarded as an idle land that preserves natural environment and maintains ecosystem, it must be developed on the basis of awareness that nature and human beings exist together. 2. Analysis of geographical factors must be advanced because it is inevitable that the development of the hill housing should be performed properly to the geographical characteristics. 3. Planning elements of ecological residential block which are possible for constructing on the hillside can be developed and applied, on the basis of geographical characteristics, by classifying them into two areas; housing estate, building and unit.