Provided is a hot balloon catheter ablation system capable of achieving pulmonary vein isolation or ablation of atrial fibrillation in a safe and efficient manner. A highly directional pressure sensor 51 is provided coaxially in an anterior portion of a catheter shaft 1 within a balloon 6. As the result, there is monitored a pressing force against the balloon onto the tissue as well as a temperature of the balloon 6, impedances, potentials, and an energization time. Further, since the directional pressure sensor 51 is provided inside the balloon 6, there is monitored a pressing force from the balloon 6 onto the tissue with accuracy without being influenced by the swirls T of the liquid, thereby securing effective ablation of the target tissues.
