1. A moving obstacle detecting device installed in or on a moving body for detecting moving obstacles in the vicinity of the moving body, the moving obstacle detecting device comprising: an image capturing unit configured and arranged to capture an image of the surroundings of the moving body; an optical flow calculating unit configured to find an optical flow corresponding to characteristic points in the image captured with the camera; a focus of expansion calculating unit configured to calculate focus or foci of expansion of the motion vectors in the optical flow found by the optical flow calculating unit; a histogram creating unit configured to create a histogram of the distribution of the focus or foci of expansion calculated by the focus of expansion calculating unit; a peak test unit configured to detect at least one moving obstacle to test peaks in the histogram, said test determining whether or not the peaks correspond to the same object if two or more peaks exist in the histogram created by the histogram creating unit.