1. A tagging method utilizing unique identification characteristics for tracking objects, comprising the steps of: reading identification information having unique characteristics of an object in a region, and capturing image data of said object; tagging the identification information of said object to the image data of said object; detecting the tagged image data of each of the objects crossing the tagged image data of other objects and re-tagging the image data of crossed objects with combination of the identification information of the crossed objects; and updating the tagged image data of the objects when the identification information of one of the objects within the region is read again by at least a reader at an endpoint or a gate by deleting the identification information of the one object being read again from the tagged image data of other objects.