PROBLEM TO BE SOLVED: To quickly and surely estimate an aggregate scattering state of a paved road and a clogged state of a drainage pavement on the basis of information acquired from the equipment mounted on a travelling vehicle.SOLUTION: A road surface photographing axis orthogonal to the travelling direction of a vehicle is set on a road surface of a paved road, a ray is obliquely irradiated to an axis perpendicular to the road surface, the road surface photographing axis is photographed from a direction perpendicular to the road surface, height information on the photographing object is acquired, research object image information continuing by connecting photographing image information on the road surface photographing axis is generated, the research object image information is partitioned into predetermined rectangular unit regions, the height information on each unit region is classified on the basis of a size of the height information included in the research object image information corresponding to e
