A measurement block 10 which moves longitudinally on a road surface includes disk-shaped first, second, and third rollers 11, 12, and 13 having the same outer diameter with a predetermined spacing set therebetween, a first coupling rod 14 which is mounted on rotary shafts of the first and second rollers in a revolving manner, a second coupling rod 15 which has the same length as the first coupling rod and which is mounted on rotary shafts of the second and third rollers in a revolving manner, a distance measurement device 16 which is mounted on the rotary shaft of the first or second roller, and a rotary encoder 18 which is mounted on the second coupling rod to detect an angle between the first and second coupling rods. Each time the measurement block moves by a length between the first and second coupling rods, the angle between the first and second coupling rods is detected by the angle detection means to thereby create a longitudinal profile based on the detected value.