An energy treatment instrument includes an electrically conductive probe having a first electrode in a distal end portion and adapted to transmit high-frequency electric current and ultrasound vibration to the first electrode, an electrode member installed on both sides of a longitudinal axis of the first electrode separately from the electrically conductive probe and provided with a second electrode, and a movable member. The movable member is installed at a distal end of the sheath member and configured to be openable and closable with respect to the second electrode. The movable member is placed at a position facing the first electrode installed at the distal end of the probe and the second electrode and includes a third electrode provided with an electrode surface configured to be able to conduct high-frequency electric current between the third electrode and the first and second electrodes.