The treatment device for electrosurgery of the present invention includes a sheath (11) that has a distal end portion (11a) and a proximal end portion (11b) a needle-like electrode portion (50) that has a distal end and a proximal end, is inserted into the sheath such that a direction toward the distal end from the proximal end becomes a direction toward the distal end from the proximal end, and treats a target site at the distal end a first electrode (51) that is provided to the distal end of the needle-like electrode portion and exposed to the outside a second electrode (52) of which the relative positional relationship with respect to the first electrode is fixed at a position separated from the first electrode toward the proximal end an insulator (53) 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.
