An image processing apparatus includes: a blood vessel sharpness image creation unit configured to create a blood vessel sharpness image representing sharpness of a blood vessel region in which a blood vessel is shown in an intraluminal image; an abnormal candidate region extraction unit configured to extract a region in which the sharpness is decreased in the blood vessel sharpness image, as a candidate region for an abnormal region in which a visible vascular pattern is locally lost; and an abnormal region determination unit configured to determine whether the candidate region is an abnormal region, based on extension information indicating a state of the blood vessel region extending in a neighborhood of the candidate region.