A radio-frequency heating balloon catheter is capable of cauterizing a target lesion in an atrial vestibule. The radio-frequency heating balloon catheter has a catheter tube including an outer tube and an inner tube slidably extended through the outer tube. An inflatable balloon is connected to an extremity of the outer tube and a part near an extremity of the inner tube, and is capable of coming into contact with a target lesion when inflated. A radio-frequency electrode serves as a counter to a surface electrode attached to a surface of a subject's body and is placed in a wall of the balloon or inside the balloon to supply radio-frequency power between the surface electrode and the radio-frequency electrode. A temperature sensor senses temperature inside the balloon, a guide shaft projects from the extremity of the inner tube and is capable of holding the balloon on the target lesion, and a guide wire extends through the catheter tube and the guide shaft.