This study is based on the 15th century’s architecture Mohwagwan and Taepyeonggwan and the architects behind it. The results were as follows: First, inline with Ming dynasty’s protocol, the King of Joseon marched with honor guard in front of his people. Therefore, the Joseon dynasty needed to match space was implemented and result in Mohwagwan and Taepyeonggwan. Second, King Taejong founded Mohwaru to share the role with Taepyeonggwan. He appropriately utilized Mohwaru as a place in manners before people enter the Seoul city wall. And He organized this architecture on the level of the palace. Third, Pak Jacheong was overseer the whole constructive process, from the selection of site, landscaping, construction, maintenance to civil engineering of Mohwaru. There are many difficulties, but he completed through the construction work owing to the protection of King Taejong. Forth, Hong Li worked with Pak Jacheong to build Taepyeonggwan and Mohwagwan from Taejong to Sejong. Supervisors in King Sejong times were required not only private capability but also understanding the Confucianism ritual. Hong Li was faithfully performed the role. Fifth, Sejong was recognized only an excellent ruler but he was also a great coordinator with a professional knowledge about architecture. These Sejong’s action fully can be seen as an architect.