Abstract
Japanese history of eugenic protection law was reviewed. Involuntary sterilization was especially focused. A review of proceedings of the National Diet, statistical reports, and medical papers were performed, as well as interviews. Before the end of World War II, "Kokumin-Yusei-Hou" was enacted. The reasons were as follows; One was negative eugenics, which aimed to reduce the "defective" persons. The other was political incentives to forbid family planning movement in order to obtain more population. On the contrary, after the war, "Yusei-Hogo-Hou" was enacted, mainly because of family planning. The number of application of sterilization has constantly decreased, however, several different patterns were observed. 1) The speed of decrease of the sterilization for maternal or medical reasons were ceased after the 1970's. 2) Involuntary sterilizations have gradually decreased to none. 3) Involuntary sterilizations for the mentally ill were constantly applied until the 1970's. The issue of translation, the reasons of the changes, and the application to the mental retarded are discussed.
