A high-frequency surgical apparatus for treating patent foramen ovale in a heart includes a flexible probe which has such a length as to allow the probe to be placed in the patent foramen ovale by passing through the blood vessel an electrode section which, being placed at a distal end of the probe, has three or more electrodes along a longitudinal direction of the probe a high-frequency power supply section which supplies predetermined high-frequency power to the patent foramen ovale via the electrode section a switching section which switches among a plurality of signal lines connected to the three or more electrodes and a high-frequency power control section which controls switching of the switching section so as to supply the high-frequency power to two electrodes.
