First, it is determined that a measurable distance of a laser radar device
is a first threshold value being an extremely short measurable distance
or below, because of dirt on a sensor or bad weather. A vehicle control
using measured data of the device is thereby prohibited. Second, it is
determined that the measurable distance is a second threshold value being
a short measurable distance or below but greater than the first threshold
value, because of dirt on a sensor or bad weather. A vehicle speed for
allowing the vehicle control using the measured data of the device is
restricted. Eventually, the vehicle control is executed under these
individual conditions.