PROBLEM TO BE SOLVED: To provide an NO sensitization-type radiation cancer treatment system capable of enhancing cancer therapeutic effect without increasing the irradiation dose.SOLUTION: In a nitric monoxide sensitization-type radiation cancer treatment system which applies a radiation beam and an ultrasonic beam, by utilizing the fact that a peak period Tp during which nitric monoxide concentration D is at its maximum occurs with an optimal delay time after an application start time Ts at which application of the ultrasonic beam to generate nitric monoxide was started, the radiation is applied concentratedly during this peak period. In addition, by utilizing the fact that the production of nitric monoxide by application of ultrasonic beam is increased specifically in certain tumor temperature range, the ultrasonic beam for nitric monoxide production is applied after the tumor is preheated to a favorable temperature range.
