To prevent volatilization, leakage accidents or the like of content by fastening a screw or a stopper plug with proper torque.

In the stopper plug, adjustment of fastening torque is carried out in reference to a bore and diameter of cam mechanism, the number of cams or the like. When stronger fastening torque is needed or a container is broken, an outer edge of an inner cap is exposed at a lower edge of a cap, so that direct fastening is carried out without the need of the cam mechanism.