PURPOSE: To shorten an obstacle detecting time and to recognize a distance up to an obstacle and a bearing direction by a simple device by providing the obstacle detector with an image forming means for forming a temperature distributing image for a front landscape by a signal outputted from an infrared- ray sensor, an extracting means for extracting a high temperature area from the image and a distance measuring means.

CONSTITUTION: The detector is provided with an infrared sensor 2, the image forming means 4 for forming a temperature distribution image for a front landscape by a signal from the infrared sensor 2, the extracting means 17 for extracting a high temperature area from the image, and the distance measuring means 3 for measuring a distance between the high temperature area and a self-vehicle. Since distance measurement only from an obstacle can be executed, signal processing volume can be reduced and the measuring time can be shortened. Since the image of the front landscape is processed, the bearing direction of the obstacle can be also detected and proper obstacle position information can be obtained by a simple device.