Through the changes of royal architectural bureau in Gungnaebu, this study attempts to find out the modern transition of traditional facilities belonging to Gungnaebu as well as the constituent of human resources in royal architectural bureau. Yeongseonsa, the royal architectural bureau in Gungnaebu after 1905, was comprised of traditional architectural engineers including Sim Euiseok, and they tried the modern transition of traditional royal facilities gradually. But, Yeongseonsa was transformed to Naejangwon Tomokgwa which was comprised of Kim Yungu and Japanese modern architectural engineers. As Kim Yungu was the modern civil engineer not architectural engineer, Japanese architectural engineers took the lead in the architectural activities of Naejangwon Tomokgwa, and Japanese architectural technology was applied to Korean royal facilities since then.