An image processing apparatus (102, 120) using two captured images captured by two image capturing units (110A, 110B) disposed on a given base line, one of the two captured images being used as a reference image and another one of the two captured images being used as a comparing image, the image processing apparatus (102, 120) comprising: a parallax computing unit to conduct a matching process and a parallax computing process, wherein in the matching process, the parallax computing unit compares a first feature value of a search target area related to a target portion for computing parallax in the reference image, and a second feature value of each of candidate corresponding areas in the comparing image respectively related to a plurality of candidate corresponding portions existing on an epipolar line that is the same epipolar line of the target portion for computing parallax, and the parallax computing unit identifies a candidate corresponding area having a second feature value matched to the first feature value of the search target area as a corresponding area or a candidate corresponding area having a second feature value within a given range from the first feature value as a corresponding area, wherein in the parallax computing process, the parallax computing unit computes a deviation amount between the target portion for computing parallax and a corresponding portion related to the corresponding area identified by the matching process along the base line direction as a parallax value of the target portion for computing parallax, characterised in that when the matching process is conducted, the parallax computing unit sets a size of the search target area in view of the deviation amount of a candidate corresponding portion along the base line direction with respect to the target portion for computing parallax, in which the greater the deviation amount of the candidate corresponding portion along the base line direction with respect to the target portion for computing parallax, the greater size is set for the search target area that is compared with a feature value of a candidate corresponding area related to the candidate corresponding portion. a parallax computing unit to conduct a matching process and a parallax computing process, wherein in the matching process, the parallax computing unit compares a first feature value of a search target area related to a target portion for computing parallax in the reference image, and a second feature value of each of candidate corresponding areas in the comparing image respectively related to a plurality of candidate corresponding portions existing on an epipolar line that is the same epipolar line of the target portion for computing parallax, and the parallax computing unit identifies a candidate corresponding area having a second feature value matched to the first feature value of the search target area as a corresponding area or a candidate corresponding area having a second feature value within a given range from the first feature value as a corresponding area, wherein in the parallax computing process, the parallax computing unit computes a deviation amount between the target portion for computing parallax and a corresponding portion related to the corresponding area identified by the matching process along the base line direction as a parallax value of the target portion for computing parallax, characterised in that when the matching process is conducted, the parallax computing unit sets a size of the search target area in view of the deviation amount of a candidate corresponding portion along the base line direction with respect to the target portion for computing parallax, in which the greater the deviation amount of the candidate corresponding portion along the base line direction with respect to the target portion for computing parallax, the greater size is set for the search target area that is compared with a feature value of a candidate corresponding area related to the candidate corresponding portion.