An image processing apparatus includes: a region detection section which detects a candidate region in which a structure having a predetermined shape is estimated to exist from an image a border pixel detection section which detects a border of the candidate region; a region setting section which sets a local region in the vicinity of and both sides of the border; a feature value calculation section which calculates predetermined feature values based on predetermined values obtained for respective pixel units of the local regions; a discrimination value calculation section which calculates a discrimination value based on calculation results of the predetermined feature values in local region groups on one side and the other side when viewed from the border; and a candidate region correction section which corrects a detection result of a candidate region based on a calculation result of the discrimination value.