A road shoulder-detecting system comprising: a first road shoulder-detecting unit configured to scan, in a traveling direction of a vehicle, a road surface in front of the vehicle and detect a road shoulder located on the road surface, a road shoulder-measuring unit configured to measure an orientation (α) of the vehicle relative to the road shoulder detected by the road shoulder-detecting unit and a distance to the road shoulder, a second road shoulder-detecting unit, and a memory unit storing a road shoulder shape of a road on which the vehicle travels as a reference road shoulder shape, wherein the road shoulder-detecting units (2a, 2b) are installed on a traveling direction side of the vehicle and are each structured to linearly scan a distance to the road surface in front of the vehicle in the traveling direction at every given angle on a scanning plane (40a, 40b), with each of the road shoulder-detecting units (2a, 2b) as a center, to form first scanning lines (L1a, L1b) where each scanning plane (40a, 40b) intersects the road surface and second scanning lines (L2a, L2b) where each scanning plane (40a, 40b) intersects an inclined surface of the road shoulder, wherein the road shoulder-measuring unit takes the points where respective first and second scanning lines (L1a, L1b, L2a, L2b) intersect as road shoulder detection points (Pa, Pb), and wherein the road shoulder-measuring unit is configured to calculate the orientation (α) of the vehicle relative to the road shoulder and the distance to the road shoulder from the reference road shoulder shape stored in the memory unit and the relative positions of the road shoulder detection points (Pa, Pb) with respect to the vehicle. a first road shoulder-detecting unit configured to scan, in a traveling direction of a vehicle, a road surface in front of the vehicle and detect a road shoulder located on the road surface, a road shoulder-measuring unit configured to measure an orientation (α) of the vehicle relative to the road shoulder detected by the road shoulder-detecting unit and a distance to the road shoulder, a second road shoulder-detecting unit, and a memory unit storing a road shoulder shape of a road on which the vehicle travels as a reference road shoulder shape, wherein the road shoulder-detecting units (2a, 2b) are installed on a traveling direction side of the vehicle and are each structured to linearly scan a distance to the road surface in front of the vehicle in the traveling direction at every given angle on a scanning plane (40a, 40b), with each of the road shoulder-detecting units (2a, 2b) as a center, to form first scanning lines (L1a, L1b) where each scanning plane (40a, 40b) intersects the road surface and second scanning lines (L2a, L2b) where each scanning plane (40a, 40b) intersects an inclined surface of the road shoulder, wherein the road shoulder-measuring unit takes the points where respective first and second scanning lines (L1a, L1b, L2a, L2b) intersect as road shoulder detection points (Pa, Pb), and wherein the road shoulder-measuring unit is configured to calculate the orientation (α) of the vehicle relative to the road shoulder and the distance to the road shoulder from the reference road shoulder shape stored in the memory unit and the relative positions of the road shoulder detection points (Pa, Pb) with respect to the vehicle.