This study aims to identify the conditions necessary for a better succession of modern architectural heritage as a daily activity in modern society. As introductory research of it, this paper has examined the state of modern architecture as “cultural properties” through the transition of administrative policies and discourses.

The idea of “cultural properties,” was firstly appeared with the Cultural Properties Protection Law of 1950. This concept has greatly expanded its scope as time goes by, away from the old-fashioned artistic point of view, under the newly introduced administrative committee system.

Both the unusual circumstance under the occupation by GHQ/SCAP and the progressive social atmosphere expecting to rebuild the social system accelerated the creation of the brand-new concept of “cultural properties,” that embraces cultural things and matters in the society, by the members of the Ministry of Education.

After 1950, the new administrative committee system, namely Cultural Properties Protection Committee, promoted the discovery and evaluation of cultural property reflecting the social trend. Consequently, the viewpoint of value evaluation has shifted from a chronological perspective to a typological perspective, which became a factor in expanding its scope to include modern architectural heritage.

Following the legislative philosophy of “cultural properties” as mankind's common heritage, the administration accepted all types of historic buildings such as shrines, temples, private farmhouses, townscapes, and modern architecture as synchronically equivalent social wealth. Legislative measures have also been put in place for a new type of “cultural properties” through establishing a new system and enhancing system operation.

In 1999, Conservation Planning was standardized as a tool for appropriate protection measures of “cultural properties” that could optimize the active use of modern architectural heritage. However, a proper understanding of its philosophy has not penetrated the world of architectural preservation in charge of actual planning work, in the world of the general construction industry, and even in the level of administrative practice involved in system operation. Thus, the system of Conservation Planning has not yet fully demonstrated its merits.