To provide a method of economically maintaining a road surface in a safe state while exerting a convenient function of a draining pavement in a circumstances that various snow melting devices contrived in recent years do not pay in terms of cost efficiency when the number of snowing days or the number of road freezing days per year is taken into consideration in some areas.

A steel pipe having pores formed therein is arranged under the draining pavement, and when road freezing is expected, air is blown from the pipe. The air blown from the pipe passes through the coarse portion of the draining pavement and reaches the road surface. The air serving as a medium is taken into the pipe via an exhaust hole of a tunnel when the location is set at a bridge, a road, etc. near the tunnel. When the tunnel etc. are not present near the location, the air is secured by feeding compressed air into the pipe by a compressor. The air fed to the pipe has a temperature as high as possible so as to dry the road surface, and snow melting or freezing prevention is achieved. An installation time and trouble are saved by unitizing a pipe installation portion, and an installation cost and an environmental load are reduced by forming a unit of the pipe installation portion of recycled materials such as reclaimed crushed stones.