This study searched the medical thought of Cheon Sun Eui (全循義). The relavance of his writings with the modern Korean Traditional Medicine, the science of food and nutrition, and the living science. His medical philosophy which was expressed in SikRyoChanYo(食療贊要), SanGaYoGok(山家要錄), ChimGuTaeKIlPeonJip(鍼灸澤日編集), etc., was investigated. The purpose of SikRyoChanYo(食療贊要) was to describe the food therapeutics before using drugs for treatment of diseases and stress the prevention of illness using foods. Second, he mentioned the science of breeding of plants and the method of food storage in his writing, SanGaYoGok(山家要錄). In this writings, the method of preparing and processing foods, storage of foods, fermentation of foods, the science of breeding of plants, etc., was mentioned. So, he could be called as a scientist. Also, he stressed the importance of food in maintaining health and curing illness in this book. Third, he wrote the good and bad luck of time and the day of getting away from the bad luck when the acupuncture and moxibustion was performed. In ChimGuTaeKIlPeonJip(鍼灸澤日編集), he reflected together the energy changes of nature and body in performing therapeutics.