PURPOSE: To reduce a member cost and to largely decrease an assembling man-hour by integrally molding a pushbutton with a Q ring and a snap ring via elastic resin.

CONSTITUTION: A pushbutton is integrally molded with elastic resin in shape for satisfying functions of a Q ring and a snap ring. A size of an outer diameter of a protrusion is formed slightly larger than a diameter of a hole of a side 5 of a watch, and mounted by press injecting at the time of assembling. Since the diameter of the protrusion of the pushbutton is larger than that of the hole when assembled with the side 5, it is press injected at the time of assembling. When mounting is completely it is fanned of an elastic member, and hence it tends to return to its original shape, and set in a pressure welding state with the hole. Thus, it can be formed in a waterproof structure. Since the shape of the protrusion is square in a reverse direction to its inserting direction, it is prevented from being removed.