This study is to investigate urban housing conditions in Seoul since 1945. The purposes of this study is to analyze the changes of housing conditions and the gap of average housing conditions and the housing norms longitudinally.For those purposes, the indicators that present the housing conditions are introduced, and the changes of average housing conditions are analyzed by social class, using Population and Housing Census and relateddata. Korean urban housing conditions has been better since 1970s in the aspect of quality. It is, however, relatively much worse than that of developed countries. The gap of housing conditions among social classes is large, especially in qualitative indicators, density and housing facilities. Comparing it with housing norm(as an ideal measurement), it is much worse.