To provide an indirect heating device of glass melting furnace, which prevents volatile material in waste gas generating out of molten glass from adhering to a heater.

The indirect heating device 12 has a heater 17, which penetrates and is arranged at the upper part of the melting furnace body 2 for heating melting glass stuff, supplied to the melting room by a main electrode placed in the middle of the melting room and whose lower end is extended out to the upper space 8 in the upper side of the molten glass in a melting room, and a heater protection tube 15 surrounding the heater 17, where slit hole 22 is formed in an upper space 8 position. A purge gas tube 28 for supplying to the inside the heater protection tube 15 a purge gas P from outside of the melting furnace body 2 is provided.