Most of researches in Korea by far on Sekino Tadashi were mainly focused on his historical view only. The main observations of this study, instead, are that; (1) his methodology of studying architectural history was closely related to his previous experiences with the conservation of the architectural heritages in Japan, and (2) his earlier activities in Korea made a significant Influence on the conservation of the architectural heritages in Korea. Sekino started his carrier after the graduation from the university by participating in the restoration sites of the architectural heritages in Japan, and his experiences at that time had founded the basis of his methodology of studying architectural history. Later, his on-site experiences were also adapted into the conservation of the architectural heritages in Korea when Korea was about to be colonized by Japan. In other words, Sekino's study on the Korean traditional architectures started from 1902 had a meaning of not only the starting point of the study on the Korean architectural history but also the starting point of the conservation of the Korean architectural heritages. Especially, Sekino's study during 1909 1912 prioritized the conservation of the architectural heritages as the main purpose of the study, and the influences of the study spanned over the entire colonial period by Japan. The influences were that; (1) Sekino's studies in 1909 1912 had outlined the colonial government's policy of the conservation of the architectural heritages, and (2) many restorations were made based on those studies.