Sudeok-sa's main hall is one of the few specimens of Koryo Dynasty wooden architecture preserved in Korea, and was repaired by Japanese conservation architects from 1937 to 1940. The feature of this repair work was proved as follows: (1) This hall was recognized its high value as a historical building, so architectural historical research accompanied a complete dismantling. (2) The Japanese conservation architects used traditional materials and techniques in Korea. (3) The building was aimed to be back to its original state. In general, the case of Sudeok-sa referred to the ideas and guidelines of Japanese conservation works.