To securely hold a lever storage part air-tightly without specially enlarging a distal end body.

The standing-up lever 15 for standing up a treater standing-up stand 4 is mounted on the lever storage part 14 formed on a side surface of the distal end body 5. A cover 20 covering the lever storage part 14, abutting to an abutting surface 5b of the distal end body 5, is fixed to the distal end body 5 with fixing screws 22. The fixing screws are a first fixing screw disposed in a body plate part 20a and a second fixing screw 22 disposed in a curved part 20b on the lower side. On the upper side of the cover 20, a turn-back part 20d is hooked astride an engagement projection 8a which constitutes a part of a restraining projecting line for stopping rotation of a distal end cap. In this way, the lever storage part 14 is held air-tightly.