PURPOSE: The stopping part connected to the knob part is narrowed on the top end to form a collar integrally and the collar is melted to close the blowing hole, thus massproducing good-quality titled stoppers of a uniform form.

CONSTITUTION: Melted glass is charged into a mold and a pressurized air is blown to effect the blow molding, whereby the cylindrical stopping part 2 connected to the hollow knob part 1 is narrowed on the top end so that the blowing hole 3 is made as samll as possible and a collar part 4 with enough thickness and height to close the hole 3 is formed. The prestopper 5 is heated entirely and the collar is melted with a gas burner 6 to close the hole 3. A cork 7 is fitted to the stopping part 2. In the present invention, the hollow part becomes a little vacuum after cooling.