To improve snow melting efficiency by providing roof-tile bars on a sheathing roof board, laying an electric heater on the roof-tile bars, and laying roof-tiles made of metal of high thermal conductivity so as to contact with the electric heater.

Roof-tiles 1 made of metal of thickness 0.5-10mm and thermal conductivity 0.15-10cal/cm.s.deg at 20°C are laid on roof-tile bars 3, the roof-tile bars 3 are fixed on a sheathing roof board 2 laminated out of heat insulating boards 6, and a cavity for passing hot air is formed between the roof-tile bars 3 and the roof-tiles 1. An electric heater 4 is laid on the roof-tile bars 3, and the roof-tiles 1 are contacted with the electric heater. By carrying current in the electric heater 4 laid on the roof-tile bars 3, heat generated from the electric heater 4 is absorbed by the roof-tiles, and heat is radiated from the surface of the roof-tiles 1. Consequently, fallen snow in the winter season is efficiently melted, and a dwelling house unnecessary for a removing work of snow on the roof can be supplied.