PURPOSE: To provide the high-frequency cautery device for medical treatment capable of making sure that an electrode catheter exists surely in the section to be cauterized by measuring the intracardiac potential in the state that the electrode catheter is in direct contact with a stimulus transmission system.

CONSTITUTION: This high-frequency cautery device supplies a high-frequency current to the myocardium of the part to be cauterized and cauterizes the myocardium of the part to be cauterized by the Joule heat generated by the supplied high-frequency current. The above-mentioned device has a modulated high-frequency current generator 11 which generates the plural modulated high- frequency electric powers P including the very weak modulated high-frequency electric power as the modulated high-frequency electric power P formed by modulating a high-frequency electric power. An energization measuring means (arithmetic section) 19 which supplies the very weak modulated high-frequency current weaker than the high-frequency current to the myocardium prior to the cautery of the myocardium of the part to be cauterized and measures the current supplied in the myocardium at the time of energization is provided.