1. An apparatus for registering face identification features, comprising: a face image retrieving portion for retrieving a face image of a person via a network using the person's name as a keyword; a face feature extracting portion for extracting features, which greatly influence identification of a person, from the face image retrieved by the face image retrieving portion; a person's name, face image and feature database for registering the face image retrieved by the face image retrieving portion and the face feature extracted by the face feature extracting portion in a state where they are associated with the person's name; an image receiving portion for video images via a network; a normalized face image extracting portion for extracting a normalized face image from face images by the unit of frame image having a face appearing thereon using the video image as input with respect to a person's name designated by the person's name, face image and feature database; a face similarity calculating portion for calculating a similarity between the feature extracted by the normalized face image extracting portion and the feature of the person designated by the person's name, face image and feature database; a face tracking portion for detecting a face from the video images frame by frame, determining identity of a person based on continuity of video images from the relationship between frames of positions of the face region obtained as a result of face detection, and specifying the zone in which the same person appears; and an additional face image extracting portion for specifying frames showing similarity exceeding a threshold value in the appearing zone of a specified person, and extracting face images of the previous and next frames thereof as additional faces; and wherein the face feature extracting portion extracts the feature from the additional image of the additional face image extracting portion and re-registers the feature of the additional image in the person's name, face image and feature database as an image of a person's name designated in the person's name, face image and feature database.