An object is to prevent a driving assistance system for a vehicle from causing a collision of the self-vehicle with a solid object by performing driving assistance. To achieve the object, when a solid object that can be an obstacle exists in the course of the self-vehicle, the driving assistance system according to the present invention determines a plurality of paths along which the self-vehicle can travel by changing the momentum thereof, designates an avoidance line along which the solid object can be avoided from among the plurality of paths, and changes the momentum of the self-vehicle in such a way that the self-vehicle travels along the selected avoidance line. If the plurality of path do not include a path along which the solid object can be avoided, the driving assistance system changes the momentum of the self-vehicle again in the middle of a path selected from among the aforementioned paths, thereby avoiding the solid object.
