A driving assistance system for a vehicle comprising: recognition means configured to recognize a solid object existing in the surrounding of a self-vehicle and generating information about a relative position of the solid object and the self-vehicle; setting means configured to set a grid map representing relative positions of the present location of the self-vehicle, an avoidance area, a safe area, and an unknown area on the basis of the information generated by said recognition means, the avoidance area being an area in which a solid object exists, the safe area being an area in which no solid object exists, and the unknown area being an area in which it is not known whether a solid object exists or not; and assistance means configured to, when the course of the self-vehicle crosses said avoidance area in the grid map set by said setting means, determine a plurality of primary paths, when said plurality of primary paths do not include a path along which said avoidance area can be avoided, select a candidate-avoidance-line from among said plurality of primary paths using an arrival distance as a parameter, characterised in that the assistance means are further configured to set, as secondary paths, a plurality of paths along which the self-vehicle can travel if the steering angle of the self-vehicle is changed in the left and right directions in predetermined angular increments at positions along said candidate-avoidance-line, designate an avoidance line from among the plurality of secondary paths, and change the momentum of the self-vehicle in such a way that the self-vehicle travels along the designated avoidance line, the primary paths being paths along which the self-vehicle can travel by changing the momentum of the self-vehicle, the arrival distance being a distance from the self-vehicle to said avoidance area, and the avoidance line being a path along which the avoidance area can be avoided, wherein when the difference between the arrival distance of a secondary path along which the self-vehicle can travel if the steering angle of the self-vehicle is changed in the left or right direction by a predetermined angle at a position along said candidate-avoidance-line and the arrival distance of said candidate-avoidance-line is smaller than a reference value, said assistance means does not perform a subsequent determination of secondary paths on the left or right side of said candidate-avoidance-line. recognition means configured to recognize a solid object existing in the surrounding of a self-vehicle and generating information about a relative position of the solid object and the self-vehicle; setting means configured to set a grid map representing relative positions of the present location of the self-vehicle, an avoidance area, a safe area, and an unknown area on the basis of the information generated by said recognition means, the avoidance area being an area in which a solid object exists, the safe area being an area in which no solid object exists, and the unknown area being an area in which it is not known whether a solid object exists or not; and assistance means configured to, when the course of the self-vehicle crosses said avoidance area in the grid map set by said setting means, determine a plurality of primary paths, when said plurality of primary paths do not include a path along which said avoidance area can be avoided, select a candidate-avoidance-line from among said plurality of primary paths using an arrival distance as a parameter, characterised in that the assistance means are further configured to set, as secondary paths, a plurality of paths along which the self-vehicle can travel if the steering angle of the self-vehicle is changed in the left and right directions in predetermined angular increments at positions along said candidate-avoidance-line, designate an avoidance line from among the plurality of secondary paths, and change the momentum of the self-vehicle in such a way that the self-vehicle travels along the designated avoidance line, the primary paths being paths along which the self-vehicle can travel by changing the momentum of the self-vehicle, the arrival distance being a distance from the self-vehicle to said avoidance area, and the avoidance line being a path along which the avoidance area can be avoided, wherein when the difference between the arrival distance of a secondary path along which the self-vehicle can travel if the steering angle of the self-vehicle is changed in the left or right direction by a predetermined angle at a position along said candidate-avoidance-line and the arrival distance of said candidate-avoidance-line is smaller than a reference value, said assistance means does not perform a subsequent determination of secondary paths on the left or right side of said candidate-avoidance-line.