1. An object tracking apparatus that tracks a position of an object displayed in video using a particle filter, the position of the object being defined by an area corresponding to an image area of the object in the video and 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; an overlap proportion calculation section that calculates a size of an overlap area of a particle of a second object with respect to a position of a first object; and a likelihood correction section that, when there is a particle for which a size of the overlap area is greater than or equal to a first predetermined value and the likelihood is greater than or equal to a second predetermined value, corrects a likelihood of a corresponding particle.