Music therapists are employed in many different settings including general and psychiatric hospitals, community mental health agencies, rehabilitation centers, day care facilities, nursing homes, schools and private practice. Music therapists provide services for adults & children with psychiatric disorders, mental retardation and developmental disabilities, speech and hearing impairments, physical disabilities, and neurological impairments, among others. But, the evaluation of the effect of music therapy has not been established. In this study we examined the measurement of a patient's body sway through the use of a video system, in order to evaluate the value of the effect of music therapy. The patient's appearance is recorded with a video camera. Next, consecutive video pictures are resolved into still and individual frame images. The body sway is extracted by using the pattern matching method from these frame images. This paper proposes that the simple measurement of the body sway is a useful element in the evaluation of music therapy.