1. A course determining system of a vehicle for determining a running course as a path along which the vehicle can run, comprising: detecting means for detecting an object that is present around the vehicle; determining means for determining, when a plurality of the objects are detected by the detecting means, whether a passable road which the vehicle can enter is present between said plurality of the objects; and course determining means for determining the running course based on at least one road including the passable road between the objects, wherein, if it is determined by determining means that there is no road which the vehicle can enter, between the plurality of objects, the plurality of objects is determined as a single object; if it is determined by the determining means that a road which the vehicle can enter is present between the plurality of objects, the plurality of objects are not determined as a single object, and the course determining means determines the running course of the vehicle based on roads including the passable road located between the plurality of objects; and if the vehicle is going to proceed into space between the plurality of objects when no road which the vehicle can enter is present between the plurality of objects, a driving assisting process is carried our, and if the vehicle is going to proceed into space between the plurality of objects when a road which the vehicle can enter is present between the plurality of objects, the driving assisting process is not carried out.