A joint surgical treatment under an arthroscope, includes: excising a treatment object of a synovial membrane, by transmitting an ultrasonic vibration to a treating portion of an ultrasonic device in a state where the treating portion is in contact with the treatment object of the synovial membrane； facing the treating portion to a treatment object of a cartilage, the treating portion being used in excising the treatment object of the synovial membrane； and removing the treatment object of the cartilage, by contacting the treating portion with the treatment object of the cartilage, and by transmitting the ultrasonic vibration to the treating portion in a state where the treating portion is in contact with the treatment object of the cartilage.
