To obtain a human obstacle detector improving detecting precision by detecting a human obstacle in a larger detecting size as it is nearer corresponding to a distance at each set detecting area.

An infrared camera 1 outputs an infrared video signal anterior to a vehicle to an obstacle detecting part 2. A navigation system 3 continuously reads traveling road information of the vehicle from a map memory to output to a detecting area setting part 4. The setting part 4 calculates the position of the road on which its own vehicle travels in an infrared video based on inputted road information. On the traveling road, three detecting areas are set corresponding to the distance and the size of each detecting area is set corresponding to a detecting size within it and the far and near of the distance. An obstacle detection part 2 binarizes video by setting the temperature of the exposed part of a human body to be a threshold value and executes graphic detection. The detected graphic is compared with the detecting size of the detecting area to detect whether it is a human obstacle. The human obstacle is position-displayed by a head up display through a display position setting part 5.