A treatment device for electrosurgery includes a sheath that has a distal end portion and a proximal end portion a needle-like electrode that has a distal end and a proximal end, is inserted into the sheath such that it is capable of advancing and retracting inside the sheath, and treats a target site at the distal end a first electrode provided at the distal end of the needle-like electrode and exposed from the sheath a second electrode fixed with respect to the first electrode at a position separated from the first electrode toward the proximal end an insulator that insulates the first electrode from the second electrode by being interposed between the first and second electrodes a first conductive portion that applies a high-frequency current to the first electrode and a second conductive portion that applies a high-frequency current to the second electrode.
