SUBJECT TRACKING DEVICE, SUBJECT TRACKING METHOD, AND CAMERA

PROBLEM TO BE SOLVED: To appropriately perform tracking even when a subject size varies.SOLUTION: A subject tracking device 100 comprises: target image setting means 104a that sets a target image in an object image; similarity calculation means 104a that calculates similarity between an initial template image not subjected to an update except for a resize and the target image and similarity between a labeling template image to be updated regardless of the resize and the target image, respectively; initial template resize means 104a that estimates a centroid position of a subject and a size thereof centering around a subject position identified on the basis of the calculated similarity and resizes the initial template image to a template size based on the estimated size of the subject; and labeling template image update means 104a that updates the labeling template image to an image of the template size centering around the estimated centroid position on the basis of the object image.