PURPOSE: To control an air quantity always to an optimum air quantity merely by lightly moving the fingers during a treatment operation by providing the above device with an opening/closing mechanism for a discharge pipe integrally with an adapter, imparting not only the opening/closing mechanism but a control mechanism for the air quantity as well to the device and making it possible to execute opening/closing and air quantity control by about the light movement of the fingers near the adapter.

CONSTITUTION: A turning disk 6 turns around a turning shaft 7 as its center and is radially bored with vent windows 19 on the outer periphery of this turning shaft 7. The spacing between these vent windows 19 and the adjacent vent windows 19 are shielding parts 20 and the outer peripheral parts of the vent windows 19 form sliding surfaces 18 on the upper surface or back surface. A stationary disk 8 is screwed to an air quantity controller fixture 9 disposed in the central part of the adapter. The turning disk 6 is fixed to the horizontal plane of a turning disk mounting part 11 existing deeper than a supporting frame 4 at the front end of the adapter. As a result, the front end 1 of the adapter is turned by the fingers, by which the shielding parts 20 of the turning disk 6 are overlapped on the vent windows 19 of the stationary disk 8 and inhalation is easily shut off.