PURPOSE: To prevent the delivery state of contents from fluctuating even if the deformation state of an elastic member varies depending upon the manner in which a depressing button is depressed.

CONSTITUTION: An elastic member 38 is provided at a delivery part 36 of a depress button 33. The member 38 is prepared by forming a rubber into one piece and deformably provided through a diaphragm 38b. And the button 33 is depressed to push a piston 20 so that the pressure inside a cylinder chamber 29 is raised thereby to open an open/closure valve 22, leading the contents in the chamber 29 via a flow passage 40 to the deliery part 36 of the button 33, so that the member 38 at the delivery part 36 is deformed, allowing the contents to be discharged to the outside through a gap produced by the deformation of the member 38. In such a blowoff device as described above, a part having a small cross-sectional area 32 is provided midway in the flow passage 40 to regulate the flow to the part 36, preventing the deformation of the member 38 from exceeding a predetermined limit.