1. A human tracking apparatus comprising: a storing unit which stores an inputted frame image; a detecting unit which detects persons photographed in the inputted frame image; a registering unit which registers already detected persons as candidates; a calculating unit which calculates indices indicating the similarity between the persons detected in the inputted frame image and the candidates registered at the time of the frame for two or more types of parameters based on the stored frame images in relation to all combinations of the persons and the candidates; a normalizing unit which normalizes the calculated indices indicating the similarity; an integrating unit which integrates the normalized indices indicating the similarity for each combination of the persons detected in the inputted frame image and the candidates; and a tracking unit which identifies a person the same as an arbitrary candidate based on the integrated indices indicating the similarity.