Previous studies on sociology and cultural anthropology insist that it is impossible to provide sufficient autonomy to clients who enroll for group care at care facilities. The purpose of this study is to analyze the nature of nursing assistant care at the national Hansen's disease sanatorium in Japan. Semi-structured interviews were conducted with 39 nursing assistants and 6 head nurses who cared for physically and socially challenged residents at this sanatorium. The investigation revealed that as a result of facing huge conflicts in the caring process, the nursing assistants had learned to appreciate the inherent life and history of residents. Thus, the nursing assistants and residents were bound together by mutual trust with a view to maximize the “autonomy of the life field.” Conflict had not stunted the self-affirmation of nursing assistants; moreover, mutual trust had reorganized the “relevant system pertaining to care” for nursing assistants, which consisted of “the unification of care” and “the equality of care.” It is suggested that group care at this sanatorium promotes the “autonomy of the life field” by valuing conflicts between nursing assistants and residents.