A mounting portion 40 including a cylinder member 30, a shaft portion 61, a piston member 60 having a button portion 64, a rigid tube 42, and an elastic tube 41 a mounting portion 40 provided between the button portion 64 and the rigid tube 42 In a state in which the piston member 60 is pressed via the button portion 64 provided on the upper P1 side of the position where the compression spring 80 and one end of the compression spring 80 in the button portion 64 are in contact with each other, the abutment of the hard cylinder 42 A first elastic member 90 which is brought into contact with the surface 42 d and is elastically deformed to seal the gap S 1 and is brought into contact with the exterior member 103 g in a state in which the piston member 60 is pushed down via the button portion 64 and elastically deformed And a second elastic member 41q sealing the gap S2 by virtue of the above-described configuration.シリンダ部材30と、軸部61、釦部64を有するピストン部材60と、硬質筒42と、弾性筒41とを具備する取り付け部40と、釦部64と硬質筒42との間に架設された圧縮スプリング80と、釦部64における圧縮スプリング80の一端が当接する位置よりも上方P1側に設けられた、釦部64を介してピストン部材60が押下された状態において、硬質筒42の当接面42dに接触され弾性変形されることにより隙間S1を封止する第1の弾性部材90と、釦部64を介してピストン部材60が押下された状態において、外装部材103gと接触され弾性変形されることにより隙間S2を封止する第2の弾性部材41qと、を具備する。
