dynamic contour extracting means comprising a processor configured for

disposing a curve with control points on the image;

summing up an internal energy indicating smoothness of the curve, an image energy indicating a concentration gradient of the image, and an external energy externally coming so as to obtain a total energy,

modifying the curve by moving the control points so that the obtained total energy becomes a minimum, and

extracting a contour of a recognition object included in the image;

detecting means for detecting the contour extracted as the road position included in the image;

imaging means for taking the image, the imaging means being configured to be disposed in a vehicle so that the image includes a horizon that is seen while the vehicle travels; and

storing means for storing a template including, inside horizontal (peripheral) boundaries and vertical (peripheral) boundaries of the template, a horizontal line corresponding to the horizon included in the taken image,

the template being provided with the control points, which include primary control points and secondary control points that are other than the primary control points,

the template including information indicating that each of the primary control points is bound to be moved based on a road shape only in one of (i) the horizontal (peripheral) boundary, (ii) the vertical (peripheral) boundary, and (iii) the horizontal line,

wherein, when the dynamic contour extracting means moves the control points including the primary control points and the secondary control points based on the template stored so as to minimize the total energy, the primary control points are bound to be moved based on the information.