To provide a precise road vertical section profile, irrespective of a temperature change in a periphery of a roller, an inclination of a road surface or the like.

A measuring block 10 is provided with the respectively paired first, second and third rollers 14-16 attached to both ends of the first, second and third rotary shafts 11-13 of the same length arrayed in parallel each other with a prescribed space, and arranged in order of front, middle and rear sides with respect to an advancing direction along a longitudinal direction of a road, the first connection rod 17 attached to the first and second rotary shafts to connect the both rotary shafts, and the second connection rod 21 attached to the second and third rotary shafts to connect the second and third rotary shafts. A speckle encoder 23 emits a laser beam to be vertical to a ground face, and finds a moving distance of the rollers based on a speckle pattern due to a reflected beam from the ground face. A linear encoder 18 detects a vertical displacement along a vertical direction of the first connection rod with respect to the second connection rod.