It is an object of the present invention to provide a radiofrequency thermal balloon catheter system capable of precisely predicting the surface temperature of a balloon which directly heats a target tissue without allowing a temperature sensor to directly contact with a balloon membrane. In the radiofrequency thermal balloon catheter system, a vibrational wave W is applied to an inside of the balloon 6 through a solution transport path 11 by means of a vibration generator 42. An in-balloon temperature sensor 8 is insulated from the electrode 7 for delivery of radiofrequency current to be fixed in the vicinity of a distal end of an inner tube 3 and then the temperature of the swirls S flowing along the inner surface of the balloon 6 is detected. In the present system, the surface temperature of the balloon 6 can be predicted by measuring the temperature of the swirls S approximate to the surface temperature of the balloon 6 by means of the in-balloon temperature sensor 8 while applying a radiofrequency current.
