11. An information attachment method of attaching meta-information for management to multimedia data, the method comprising: monitoring whether or not a search frequency, in predetermined periods, of a search word satisfies a predetermined criterion, wherein the predetermined criterion is satisfied if a ratio of a current search frequency of the search word to a past search frequency of the search word is equal to or more than a predetermined ratio; determining whether or not at least a portion of the search word matches a character recognition processing result of the multimedia data when the search frequency of the search word is determined to satisfy the predetermined criterion; and registering the search word as meta-information of the multimedia data when at least the portion of the search word matches the character recognition processing result; wherein the search word is registered, when the search word is registered a meta-information of the multimedia data, by assigning priorities in accordance with a certainty factor of the character recognition processing result matching the search word, wherein the past search frequency is obtained from first average search frequencies of each search word during a first time period prior to a predetermined time, and the current search frequency is obtained from second average search frequencies of each search word during a second period within a specified time length of the from a time of acquisition of the search word, the second period being shorter than the first period.
11. An information attachment method of attaching meta-information for management to multimedia data, the method comprising: monitoring whether or not a search frequency, in predetermined periods, of a search word satisfies a predetermined criterion, wherein the predetermined criterion is satisfied if a ratio of a current search frequency of the search word to a past search frequency of the search word is equal to or more than a predetermined ratio; determining whether or not at least a portion of the search word matches a character recognition processing result of the multimedia data when the search frequency of the search word is determined to satisfy the predetermined criterion; and registering the search word as meta-information of the multimedia data when at least the portion of the search word matches the character recognition processing result; wherein the search word is registered, when the search word is registered a meta-information of the multimedia data, by assigning priorities in accordance with a certainty factor of the character recognition processing result matching the search word, wherein the past search frequency is obtained from first average search frequencies of each search word during a first time period prior to a predetermined time, and the current search frequency is obtained from second average search frequencies of each search word during a second period within a specified time length of the from a time of acquisition of the search word, the second period being shorter than the first period. 14. The information attachment method according to claim 11 , wherein the determining compares both a character recognition result acquired from images of video data and that acquired from speeches of the video data with the search word for determination.