1. An image processing device for adjusting a disparity value between a left-eye image and a right-eye image, the image processing device comprising: a feature point extraction unit that extracts feature points from each of the left-eye image and the right-eye image; a number-of-non-corresponding-points calculation unit that calculates, in a case where the feature points in one image among the left-eye image and the right-eye image, which are extracted by the feature point extraction unit, are shifted a certain distance in a horizontal direction, the number of feature points in the one image that do not correspond to the feature points in the other image, for each shift distance; and a disparity value adjustment unit that adjusts a disparity value between the left-eye image and the right-eye image in accordance with the number calculated for each shift distance by the number-of-non-corresponding-points calculation unit.