ultrasound treatment device, and the sheath, the probe tip surface from the distal end of the sheath a probe to be inserted in a state positioned at the front end direction side inside the sheath, and a suction passage defining portion defining a suction passage along the longitudinal axis in the interior of the probe, between the peripheral portion and the probe outer periphery sheath I and a gap defining section for defining a gap therebetween. The ultrasonic treatment apparatus, the suction passage suction port communicating with the, in a state where part of a non-exposed portion of outer circumference side is covered with the sheath of said suction port, suction port regulations prescribed in the probe outer periphery It includes a section, and an opening defining portion that defines the opening of the sheath outer periphery of said gap and communicating.超音波処置装置は、シースと、前記シースの先端よりプローブ先端面が先端方向側に位置する状態で前記シースの内部に挿通されるプローブと、前記プローブの内部に長手軸に沿って吸引通路を規定する吸引通路規定部と、シース内周部とプローブ外周部との間に隙間を規定する隙間規定部と、を備える。前記超音波処置装置は、前記吸引通路に連通する吸引口を、前記吸引口の一部が前記シースにより外周方向側が覆われる非露出部分となる状態に、前記プローブ外周部に規定する吸引口規定部と、前記隙間と連通する開口をシース外周部に規定する開口規定部と、を備える。
