PURPOSE: To improve the heat insulating effect and shorten the work period by connecting snow melting boards incorporating a radiating pipe and pouring mortar or expanded urethane from the bottom of snow melting board to secure the board to the roadbed.

CONSTITUTION: Snow melting boards 3 incorporating a radiating pipe 2 are arranged on the roadbed 1 onto which a particulate material is placed and rolled. The snow melting boards 3 are connected at the same height by using leveling adjusters 12 installed on the bottom of the board and bars 5. Then, mortar or expanded urethane is poured between the roadbed 1 and the snow melting board 3 through grouting passages 6 disposed on the bottom of the board. Next, a radiating pipe inlet 7 and a radiating pipe outlet 8 are connected to each other by a connecting member 9, and the first radiating pipe inlet 7 and the last radiating pipe outlet 8 of snow melting board set are connected to a water supply main pipe 10 and a return main pipe 11, respectively. This method shortens the work period, improves the heat insulating effect, and provides a flat road surface.