This article explores how the East Asian medicine had been developed in Goryeo Dynasty and Joseon Dynasty. In particular, it focused on the medical textbooks of Goryeo and Joseon. As the Chinese medicine entered in the Three Kingdoms Period, intellectuals accepted knowledges of the Chinese medicine, and a small number of the ruling class benefited from the Chinese medicine prescriptions and imported medicine. In the late period of Goryeo Dynasty, the Hyangyakgugeupbang(鄕藥救急方) was published. It paid attention to the drug properties of the Korean medicine. This book contains the long-accumulated knowledge of the Korean medicine which used local drugs “Hyangyak.” In Joseon, the government and medical scientists investigated the reality of the Korean medicine on a national scale. It carried out for increasing types and productions of the Korean medicine. As a result, the era of Dongui(東醫) was opened. The goal of treating all diseases of Joseon with the medicine of Joseon was achived. However, medical theory of the Hyangyakjipseongbang(鄕藥集成方) printed in 1433 was quite insufficient. Thus, by the successive publication of the Euibangyoochui(醫方類聚) printed in 1477 and the Donguibogam(東醫寶鑑) printed in 1613, the medical theory tailored to the ideological, socioeconomic and medical situations of Joseon was completed. It was not until the end of the Joseon Dynasty that Lee Je-ma''s Donguisusebowon(東醫壽世保元) was able to overcome the Donguibogam. Lee Je-ma classified every people into four distinctive types: greater yang[tai yang] person, lesser yin[shao yin] person, greater yin[tai yin] person, and lesser yin[shao yin] person. This theory insisted proper treatment for each type in accordance with individual differences of physical features and temperament. His theory has many modern aspects. Korean Traditional Medicine could be modernized by itself.