To provide a steam heating device that efficiently increases the temperature of an object to be treated internally and externally and significantly reduces heating time.

The steam heating device includes a steam generating source and a steam supply tube 33 supplying steam of high temperature and high pressure in a vulcanizer 30, and a microwave circuit 35 and a microwave power source 44 supplying microwave power in the vulcanizer 30. In the steam heating device, rubber products 46 such as an unvulcanized rubber, a semi-vulcanized rubber and the like housed in the vulcanizer 30 are exposed to heating mediums including the steam of high temperature and high pressure and the microwave power, and temperature can be increased in a short time for vulcanizing the rubber products 46 by the synergistic effect of the steam of high temperature and high pressure and the microwave power.