The "Naegyeongseupyubangron(內經拾遺方論)", written by Nakyonggil(駱龍吉), is an ancient book of Bangron(方論). The exact time period of this book is unknown. To estimate its written time, we compared the contents of this book to other sources on the cause of diseases, the description of symptoms, the transmission of diseases, and treatments. In addition, we analyzed the features of the book by comparing it to other books of Bangron(方論). As a result, we estimated the approximate time period that it was written and gained a better understanding of the ancient medicine. We reached several conclusions through this study. 1. The approximate time period of "Naegyeongseupyubangron(內經拾遺方論)" is that of the Southern Song(南宋) dynasty of China, probably after "Saminbang(三因方)" between 1174 and 1279. 2. Nakyonggil(駱龍吉) was influenced by Wangbing(王?), Sonsamak(孫思邈), Yuhagan(劉河間), Jinmutaek(陳無擇). and he influenced "Uibanggo(醫方考)". 3. The "Naegyeongseupyubangron(內經拾遺方論)" is the most comprehensive book among the books of Bangron(方論) because of its analysis of the "Hwangjenaegyeong(黃帝內經)" and its connection to the treatment of ancient diseases in Oriental Medical History.