To provide a heat-insulating vessel structure which can decrease the volume of a heat-insulating layer and the heat dissipation loss without using a high-cost vacuum heat-insulating vessel or the like, enables the miniaturizing of a device and the improvement in thermal efficiency, can greatly reduce the time and labor in the application of a heat-insulating layer, and allows maintenance to be easily performed.

The structure is characterized as follows: a vessel 15 is provided with a double-layer structure composed of an inner heat-insulating layer 15a and an outer heat-insulating layer 15b; the inside of the inner heat-insulating layer 15a is used as a channel 17 of a combustion gas generated by burning a fuel with air for combustion; and the space between the inner heat-insulating layer 15a and the outer heat-insulating layer 15b is used as a supply channel 18 of the air for combustion. The air for combustion introduced into the supply channel 18 is preheated by the combustion gas present in the channel 17 and then supplied to the inside of the inner heat-insulating layer 15a.