1. An image processing apparatus comprising: (A) an image obtaining unit configured to obtain a time-sequential image obtained in order of a start image, a plurality of intermediate images, and an end image; and (B) a route determining unit configured to determine a route that passes from the start image to the end image via at least one of the plurality of intermediate images for the time-sequential image, wherein the route determining unit includes: (a) an image selecting unit configured to select a plurality of first selection images from among the plurality of intermediate images; (b) a conformity calculating unit configured to calculate a first conformity based on image quality of the first selection image and a similarity between the start image and the first selection image, for each of the plurality of first selection images; and (c) a conformable image determining unit configured to determine a first conformable image from among the plurality of first selection images on the basis of the first conformity corresponding to each of the plurality of first section images.