A double insulating wall structure heating furnace capable of preventing its inner pipe whose strength has decreased due to high-temperature heating from being damaged. A double insulating wall structure heating furnace 1 includes an outer pipe 2 and an inner pipe 3 disposed inside the outer pipe 2, in which a sealed space 8 formed between the outer and inner pipes 2 and 3 is depressurized and a heating space 13 formed inside the inner pipe 3 is heated, and in which a tubular reinforcing member 6 is disposed so as to cover an outer circumference of the inner pipe 3, the tubular reinforcing member being formed of a material having a higher heat resistance and a higher strength than those of the material of the inner pipe 3.