1. A driving control system for a vehicle, comprising: a map information output means for outputting a map; a vehicle position detecting means for detecting a vehicle position of a subject vehicle on the map; a vehicle speed detecting means for detecting a vehicle speed; a passable area determining means for determining a turning radius of the vehicle based on the detected vehicle speed and determining a passable area on the map which is safely passable by the vehicle based on the determined turning radius; a passability/impassability judging means for deciding that the vehicle is safely passable within dimensions of an oncoming portion of road which is in front of the vehicle position in a traveling direction when the road portion is included in the passable area of the map; and said map information output means, said vehicle position detecting means, said vehicle speed detecting means, said passable area determining means, and said passability/impassability judging means being operatively interconnected.