To reduce the operating cost of a device by conserving energy in the vulcanizing device for a tire in which inert gas is preheated by a heater.

The vulcanizing device is constituted by providing a vapor source 11 for supplying vapor of high temperature into an inflated bladder 7 through a steam pipeline 10 at the vulcanization, providing a gas source 14 for supplying inert gas into the bladder 7 through a gas pipeline 13 and providing a heater 16 for heating inert gas on the way of the gas pipeline 13. In this case, the interval of the gas source 14 and the heater 16 is formed into double pipeline structure consisting of metal. The inside passage of the double pipeline is constituted into the gas pipeline 13 and on one side, the outside passage is formed into a part of the vapor pipeline 10.