Tracking candidate storage means 81 stores a plurality of candidates for one or more objects to be tracked. Control means 82 controls a likelihood of each of the plurality of candidates. The tracking candidate storage means 81 stores, for each of the plurality of candidates, label information identifying which object the candidate corresponds to, position information indicating a position of the object, and a likelihood. The control means 82 controls the likelihood of a candidate, according to the label information of one or more other candidates around the candidate determined based on the position information of the candidate.