1. An object extraction device comprising: a first object extraction calculating device that finds the object extraction image by carrying out object extraction calculations for extraction an object by using a predetermined first calculation parameter on a plurality of photographed images having a parallax with respect to the same object; and an incorrect outline extraction processing device that extracts an outline from an object extraction image found by said first object extraction calculating device and extracts as an incorrect outline a straight line segment having a length exceeding a predetermined threshold value within the extracted outline.