In order to provide a small, stereo camera with stable errors of distance measurement, there are provided: an image acquisition unit that acquires plural images imaged by plural imaging units; a first region processing unit that divides each of the plural images acquired by the image acquisition unit into first regions composed of predetermined plural pixels, and measures a distance for each of the divided first regions to generate a first distance image; a target object extraction unit that extracts a target object from the distance image or the image, and extracts a second region composed of the plural first regions including the extracted target object; an error factor identification unit that extracts a predetermined representative value from the inside of the second region, compares the brightness value of an arbitrary pixel in the second region with that in a correspondence region up to the position moved from the arbitrary pixel by a disparity represented by the representative value, and determines an error factor on the basis of the comparison result; and a second region processing unit that determines a weight value on the basis of the error factor, and measures a distance for each second region using the weight value to generate a second distance image.