Firstly this article deals with the history of sanatoriums for leprosy patients especially from the standpoint of famous leaders like Souichi Iwashita, Kensuke Mitsuda, who was called the father of leprosy patients, and Fumio Hayashi, who was a faithful disciple of Mitsuda. Secondly it analyzes the attitude of Tadao Yanaihara toward leprosy patients.He did not regard leprosy as a heavenly punishment, but as a heavenly grace and insisted on the hope of the resurrection of the body. He also esteemed the dignity of the patients and their right to live. He visited several sanatoriums likeTama Zenshoen Sanatorium, the National Leprosarium( 多摩全生園), Nagashima Aiseien( 愛生園), and Hoshizuka Keiaien( 敬愛園) and held lecture meetings for patients in each sanatorium. Thirdly this article evaluates the problems of the compulsory segregation policy and the movement of" no leprosy patients in each prefecture." How did Yanaihara respond to such compulsory segregation? Although he did not resistthe segregation policy, at least before the antibiotic Promin was invented in 1943, he did not think that leprosy was a shameful disease or that the purity of the nation should be maintained. He preferred the dignity of patients to thepurification movement. He wanted to build communities of mutual love and assistance in sanatoriums. Moreover, he even asked leprosy patients to pray for world peace.