To recognize correctly a preceding vehicle on a self-lane by altering the distance for determining with an obstruction on own lane, according to an established own lane determining width and shortening the distance more so that own lane determining width is narrower.

In a following distance measuring apparatus for choosing the preceding vehicle out of a preceding vehicle candidate that exists on own lane by irradiating a plurality of laser beams at a range from which the vehicle front differs, detecting the position and the distance of the obstruction, establishing the distance for determining with the obstruction on own lane for every laser beam, and repeating the detecting action of the preceding vehicle candidate on own lane, by letting an obstruction which exists below in the distance be the preceding vehicle candidate; the apparatus extracts the preceding vehicle candidate considered that is the same as that for the preceding vehicle candidate that has chosen as the preceding vehicle by a laser preceding vehicle candidate detecting action, establishes own determining width of the surface larger than own width of the surface of a travel motion road when the preceding vehicle candidate that has extracted is single, establishes own lane determining width of the surface narrower than own lane width of the surface, when the vehicle candidate that has extracted is a plurality, alters the distance for determining width the obstruction on own lane according to the established own lane determining width of the surface, and shortens the distance, so that the self-lane determining width of the surface is narrow.

COPYRIGHT: (C)2007,JPO&INPIT