In order to make it possible to previously specify which of two members the rubber-like elastic part pinched between the two members attaches to, and to improve workability of rework or the like, an attachment member specifying structure is provided in the rubber-like elastic part so that the rubber-like elastic part is surely detached from one member and attached to the other member at a time of moving the two members apart from each other, preferably by forming a contact area with one member in the rubber-like elastic part smaller than a contact area with the other member, by forming a surface treated portion by matte finishing or the like in a contact area with one member in the rubber-like elastic part, or by forming a projection-like spring portion elastically pressed to one member so as to achieve a spring effect.