5 New Towns of Seoul metropolitan area that have already been built over about 20 years, as with other urban regeneration projects are under tremendous development pressure for change. As for this circumstances, the purpose of this study is to establish the concept of sustainable conversion and to suggest the detailed elements of sustainable conversion for housing estates. For the purpose of this study, the current tendencies of developed countries such as Japan, England, and Germany are reviewed. The concept of year-to-year variation and deterioration in housing estates and sustainable development, which are closely related concept with sustainable conversion were investigated, and drawn the concept of sustainable conversion of housing estates. The planning elements were suggested for sustainable conversion in housing estates based on above concepts in the aspects of social, economic, environmental, cultural and system. The results of this study are expected to serve some clue for dealing with the practice of sustainable conversion in housing estates.