PURPOSE: To provide a hot balloon catheter which excels in the safety and can control the heating temp. accurately.

CONSTITUTION: A balloon 2 capable of inflating and shrinking is fixed to the tip of a catheter 1, and inside of the balloon 2, an electrode for high-frequency heating and a thermo-sensor 5 are installed. A temp. control means adjusts the output of a high-frequency wave generating device on the basis of sensing signals from the thermo-sensor 5 and heats electrode 3 so as to heat the surface of the boon 2 to a preset temp. level. Thereby a blood vessel strictured part can be pressed wider in good performance by inflating the balloon 2 and crushing in the condition that the strictured part is heated and also adjustability for the output of the high-frequency generating deviced enables expanding in the condition that the heated temp. of the strictured part is kept constant.