PURPOSE: To provide a roof structure having an insulating function which equalizes a construction work on a roof surface with that which is not used in cold districts.

CONSTITUTION: Roof panels 40a and 40b are framed with a vertical core material and a horizontal core material and a face material is fixed with the single surface, thereby constituting the roof panels. An insulating material 26 is laid out in an area surrounded by each core material on the bottom of the roof panels 40a and 40b. As a roof construction work above the roof panels 40, a water resistant sheet 20, a permanent metal sheet 28 and a roofing material 30 and a surface finishing material on the top are only required to be installed. The specifications for a construction work on the roof panels 40a and 40b are substantially equivalent to the specifications required for a construction work in cold districts.