disclosed are an electrode for high - frequency surgery , a high - frequency surgery device , and a method for controlling same , wherein the electrode for high - frequency surgery can be easily inserted and moved inside the lumens inside the body , and can expand a conduction area of a high - frequency current after reaching an area to be treated . the electrode for the high - frequency surgery , according to the present invention , comprises : a balloon ; and a conductive structure , which is arranged on the outside of the balloon and the exterior shape of which varies according to the volume of the balloon .