1. An obstacle detection device for a vehicle comprising: area determining means for determining a detection area extended forward of a running vehicle for detecting an obstacle, split means for splitting the detection area into a plurality of small split zones, detecting means for detecting an obstacle for each of the small split zones produced by splitting the detection area, judging means for judging a degree of danger of the obstacle in the detection area based on a relationship between said obstacle and the running vehicle, and control means for controlling the vehicle based on said degree of danger.