A navigation apparatus includes: a storage portion that stores three-dimensional image data of an examinee that is previously acquired; an organ extracting portion that extracts a predetermined organ from the three-dimensional image data; a first region designating portion that designates a tumor in the three-dimensional image data; a blood vessel extracting portion that extracts a plurality of blood vessels that are inside the organ from the three-dimensional image data; a blood vessel classifying portion that classifies the blood vessels into either arteries or veins; and a second region extracting portion that, based on three-dimensional image information of the blood vessels, extracts a tumor resection region that is a region that is classified based on anatomical features of the organ and that includes a tumor.