Geum-Won dynasty is the era which totalized the every medical attainments of before Song dynasty and appeared some medical practioners who found new medical theory based upon this, and is important time for various developments of the oriental medical theory. At this time of the era, the representative practioners are called the four noted physician of Geum-Won dynasty. Jang Won-So who influenced the formation of the theory of the four noted physcian of Geum-Won dynasty, originated new theory by joining the theory of "Nae-Gyung" with his own medical experience. The results can be summarized as follows after studying his life and idea of medicine. 1. Jang Won-So, courtesy name is Gyeol-Go, came from Yeog-Joo and it is unknown that when he was born and dead, but he lived in 11C. At 27, after failed in a Jin-Sa examination, he started medical study, and widely spreaded his medical art by healing the Yoo Wan-So's Sang-Han disease. 2. There are many Jang Won-So's writings, such as "Eui-Hag-Gye-Won" which is the condensation of his idea of medicine, "Jin-Joo-Nang" which is greatly contributed to development of Herbology, "Jang-Boo-Pyo-Bon-Han-Yeol-Heo-Sil-Yong-Yag-Sig" which is the sample of Jang-Boo-Byun-Jeung-Lon-Chi, and "Yag-Joo-Nan-Gyung" "Gyeol-Go-Ga-Jin" "Gyeol-Go-Joo-Sug-Hwa-Mag-Gyeol" "Gyeol-Go-Bon-Cho" "San-Yog-Bo-Sang-Bang" which are known do not existing. 3. Jang Won-So's study about Jang-Boo-Byun-Jeung was influenced by "Nae-Gyung" "Jung-Jang-Gyung" "So-A-Yag-Jeung-Jig-Gyeol" etc. and outline by Han-Yeol-Heo-Sil and the change and prognosis of the state of disease can be decided by Saeng-Sa-Yeog-Soon, so he contribute to development of lang-Boo-Byun-Jeung-Lon-Chi of posterity. 4. Jang Won-So succeeded and develope the theory of the herbs of Oh-Jang-Go-Yog-Bo-Sa and about Ki-Mi-Seung-Gang-Boo-Chim etc. appeared on "Nae-Gyung", especially invented such as Kwi-Gyung-Lon, In-Gyeung-Bo-Sa-Seol, Jang Boo-Pyo-Bon-Yag-Sig and he enriched the content of pharmacological theory, so he motivated various development of herbalogical theory. 5. Jang Won-So's idea of On-Yang-Bi-Wi directly influence Lee Go's assertion of Bi-Wi-Lon, idea of Go-Geum-I-Gue-Seol presented theological basis of posterior medical practioners formation of prescription, so the way of drug usage greatly developed. 6. Jang Won-So's theory of the lang-Boo-Byun-Jeung and herbology directly influenced to Lee Go, Wang Ho-Go, Na Chen-Ik, lang Byeok etc. so he became the father of Yeog-Soo class and indirectly influenced to Seol Gi, Jo Hen-Ga, lang Gae-Bin, Lee Jung-Jae etc. of Myeng dynasty, so the On-Bo class has been formed. Like this, because, his idea of medicine developed at various aspect and greatly influenced to posterity, Lee Si-Jin said "Since the emergency of "Nae-Gyung", Jang Won-So is the only man who greatly enhance medical principle.", so it is clear that this is not unfounded expression at all.