This thesis studied on the establishment and function of Jonaewon as a medical center in Sangju District. This paper was based on the existing study and data regarding Jonaewon. I have checked the background for establishing Jonaewon in two sides: local order reconstruction for noblemen in Sangju District and improvement in a regional medical system. And I have carefully researched on its first founder and its management. Jonaewon was the medical center founded by a meeting made up of a lot of clans gathering in Sangju District. Nevertheless, it was characteristic that medical benefit was open to ordinary people in Sangju. And I have made reconstruction through exactly criticism of historical materials about operation and function of Jonaewon, and its change processes. Especially, I have carefully researched focusing to a function as a medical center of Jonaewon. The reason is that it is the most basic function of Jonaewon. The function of Jonaewon operated as a medical center during 180 years from 1599 to 1782. Undoubtfully, Jonaewon had various hardship in operating. It experienced trouble to get from a threat to existence as a medical center during the middle of 17th century. After that, its function as a medical center weakened a lot only to completely stop in the end of 18th century. The existence of Jonaewon is a representative example of regional social changing trend that a medical system led by the government was changed into a medical system by the clans of the noblemen privately.