This study examines the religious origin of the Tagahōin-ryū 多賀法印流, a medical school which flourished in the early 17th century. It was founded by Shūyo Hōin 宗与法印 （?- 1654）, a priest of the Taga Taisha shrine多賀大社. Various Buddhist ideas can be found in the medical publications of the school. In this study, focus is placed on three points, and it is demonstrated that Tagahōin-ryū medicine is actually based on preceding Buddhist medicine traditions. First, attention is paid to ideas about the cause of illness regarded as the outcome of one’s state of mind. Second, belief in Yakushi Nyorai 薬師如来 is noticed. Offering proper treatment is what doctors are trained for, and the treatment itself is protected by Yakushi. The third point stresses the Buddhist interpretation of fetal growth in the mother’s womb. The foetus is said to grow under the protection of thirteen buddhas. These three points are very similar to what is found in Kajiwara Shōzen’s 梶原性全 （1265-1337） Ton’ishō 頓医抄 and Dairyū’s 大龍 Sanken I’chisho 三賢一致書 （1649）. Considering the above, it is thus clear that the idea of the Tagahōin-ryū is based on the tradition of Buddhist medicine.
