1. An object tracking apparatus that tracks a position of an object displayed in video using a particle filter, the object tracking apparatus comprising: a feature calculation section that generates a plurality of particles indicating candidates for a position of the object, and calculates a feature of an image of the object and features of images of the particles; a likelihood calculation section that calculates, for each particle, a likelihood of that particle being a position of the object from similarity between a feature of an image of that particle and a feature of an image of the object; a position estimation section that estimates a position of the object based on the calculated particle likelihood; and a likelihood correction section that corrects the likelihood when there are a plurality of objects and a plurality of positions estimated in correspondence to these overlap.