This paper studied Lee Han-Choel’s career who was known as the first Korean who had participated in several survey and repair projects of Korean historic buildings as a field engineer during the Japanese colonial era. This paper investigated documents and drawings to find out what he had done specifically in the field, and distinguished the records he had written by handwriting comparison method. In addition, the author analyzed the contents of the articles he published and clarified their significance in Korean architectural history. Through this study, the author expected to clarify Lee’s historical status as the first Korean modern expert in the field of historic building conservation, and to supplement the research for the history of Korean during the Japanese colonial era.