In an arthroendoscopical surgical method, a resection target area, which is emphasized by fluorescence with use of a fluorescent agent under excitation light, is identified on a meniscus, and a resection line or an imaginary resection line is drawn. Using an ultrasonic treatment tool and an arthroscope, the resection target area is resected by a probe which generates ultrasonic vibrations, based on the resection line or imaginary resection line under visible-light illumination, and an inclined resection surface is formed.