In clinical medical service and health care practice, using music as a way of intervention has become gradually more common and popular. But in the aspects of definition, theoretical foundation, professional training and practice application of music therapy, there are apparent disagreements between different domains. The purpose of this paper is tried to clarify briefly the historical development, definitions, theoretical backgrounds and different groups of music therapy. The present interventions of music therapy in Taiwan are mostly ”music oriented”, focus on the practical use of music. They don't belong to that kind of ”psychotherapy”, which is conducted by professional psychotherapists. Due to the diverse theoretical backgrounds by practicing music therapy, this paper suggests to divide it into three different fields: (1) the field of ”neuro-physiology” and ”medical/nursing care” (2) the field of professional music therapists and (3) the field of social care