An energy treatment instrument comprising: a probe including a treatment section in a distal portion thereof; a sheath configured such that a cavity portion, through which the probe is inserted, is formed in an inside of the sheath; a jaw rotatably attached to the sheath, and configured to be openable and closable relative to the treatment section, the jaw including an abutment surface which is abuttable on the treatment section, and the jaw being configured such that a jaw cavity is formed in an inside of the jaw; a liquid feed conduit configured to communicate with the jaw cavity, and to cause a supplied liquid to flow into the jaw cavity; a liquid outflow portion (65A, 65B, 66A, 66B, 103A, 103B, 108) configured to make the jaw cavity open to an outside of the jaw at a position located on a distal direction side with respect to a proximal end of the abutment surface, and to cause the liquid, which flows into the jaw cavity from the liquid feed conduit, to flow out toward a treatment section side; and a collision wall (67, 105) provided in the jaw, and configured such that the liquid flowing in the jaw cavity collides with the collision wall, (67, 105) and thereby the collision wall (67, 105) prevents outflow of the liquid to the outside of the jaw from a region located on a proximal direction side with respect to the proximal end of the abutment surface characterized in that the jaw further includes: a jaw support portion attached to a distal portion of the sheath; and a jaw swing portion swingably attached to the jaw support portion on a jaw closing direction side of the jaw support portion, the jaw swing portion being configured such that the abutment surface is provided on the jaw swing portion and the jaw cavity is formed between the jaw swing portion and the jaw support portion in a jaw closing direction and a jaw opening direction. a probe including a treatment section in a distal portion thereof; a sheath configured such that a cavity portion, through which the probe is inserted, is formed in an inside of the sheath; a jaw rotatably attached to the sheath, and configured to be openable and closable relative to the treatment section, the jaw including an abutment surface which is abuttable on the treatment section, and the jaw being configured such that a jaw cavity is formed in an inside of the jaw; a liquid feed conduit configured to communicate with the jaw cavity, and to cause a supplied liquid to flow into the jaw cavity; a liquid outflow portion (65A, 65B, 66A, 66B, 103A, 103B, 108) configured to make the jaw cavity open to an outside of the jaw at a position located on a distal direction side with respect to a proximal end of the abutment surface, and to cause the liquid, which flows into the jaw cavity from the liquid feed conduit, to flow out toward a treatment section side; and a collision wall (67, 105) provided in the jaw, and configured such that the liquid flowing in the jaw cavity collides with the collision wall, (67, 105) and thereby the collision wall (67, 105) prevents outflow of the liquid to the outside of the jaw from a region located on a proximal direction side with respect to the proximal end of the abutment surface characterized in that the jaw further includes: a jaw support portion attached to a distal portion of the sheath; and a jaw swing portion swingably attached to the jaw support portion on a jaw closing direction side of the jaw support portion, the jaw swing portion being configured such that the abutment surface is provided on the jaw swing portion and the jaw cavity is formed between the jaw swing portion and the jaw support portion in a jaw closing direction and a jaw opening direction. a jaw support portion attached to a distal portion of the sheath; and a jaw swing portion swingably attached to the jaw support portion on a jaw closing direction side of the jaw support portion, the jaw swing portion being configured such that the abutment surface is provided on the jaw swing portion and the jaw cavity is formed between the jaw swing portion and the jaw support portion in a jaw closing direction and a jaw opening direction.