A stopper change device (10) includes an airtight chamber body (21) detachably mountable on a head of a bottle, a gas supply port (19) for supplying N gas to the chamber body, an air vent valve (57) for discharging air from the chamber body, a first supporting structure (28) movable upward and downward for supporting a corkscrew, and a second supporting structure (34) movable upward and downward for containing a substitute stopper. The first and second supporting structures are mutually position changeable, and one of them is selectively placed above an opening of the bottle. When the first supporting structure (28) is placed above the opening, a bottle stopper can be pulled in N gas atmosphere. On the other hand, when the second supporting structure (34) is placed above the opening, the substitute stopper is mountable on the head of the bottle in N gas atmosphere. By changing the bottle stopper with the substitute stopper using this device, entering of air in the bottle as a cause of deterioration in a quality can be prevented.