A radio-frequency thermal balloon catheter includes a catheter tube including an outer tube and an inner tube, a balloon connected to an end part of the outer tube and an end part of the inner tube, and capable of coming into contact with a target diseased part when inflated, a radio-frequency electrode placed in the wall of the balloon or inside the balloon to transmit radio-frequency current, a lead wire electrically connected to the radio-frequency electrode, a temperature sensor capable of measuring temperature inside the balloon, and a swirling current producing means for making a fluid contained in the balloon swirl in a vertical plane in the balloon so as to reduce an upper-lower temperature difference between an upper part and a lower part of the interior of the balloon due to convection of the fluid to naught.
