This study is focusing on the Nagan Folk Village, primarily because of its historical and cultural values. The purpose of this study, accordingly, analysis the fact of the dwelling change through spot-survey and case-investigation, and is to find a way to improve for the rational preservation of the traditional dwelling analyzing on the actual condition and the reason for such changes in the Nakan Folk Village. The dwelling change is stemmed from the physical factors, and some modifications of internal composition, exterior formation, building equipment. As a result, The changes of internal composition are included in the reduction of garnering room, the enlargement of bed/service room, the establishment of mechanical room. The changes of exterior formation with structural material are included in the glass door for the internalization of 'TOEMARU', the extra glass door for the brightening of room, the cement plastering for the endurance of wall. The changes of building equipment are included in the establishment of oil-boiler, wash closet, sink for convenient life All houses should be graded on their qualitative value, managed in a cycle. And its own criterion for acceptable deformations should be established.