PURPOSE: A nickname use method for guaranteeing anonymity in data management for personal information protection is provided to identify a user with difficulty through record change trace, thereby searching information for a specific person with reinforced anonymity. CONSTITUTION: A sensitive attribute used for individual identification is managed in a safe data management server which access is limited. An individual information providing service which guarantees anonymity is performed through a server which manages data record identification, an anonymity attribute, and other attributes. When a nickname for a record of a specific person is changed, a database modifies nicknames of total records of which anonymity attributes are the same as anonymity attributes of a corresponding record(405). [Reference numerals] (201) Select a record for an extracted nickname; (202) Set a new nickname for the selected record; (203) Transmit existing nickname-new nickname correction information to a database server; (401) Select a record with a nickname to be changed; (402) Extract the anonymity attributes of the selected record; (403) Select a record with the attribute which is the same as the extracted attributes; (404) Extract the nicknames of the selected records; (405) Correct the nicknames in an anonymity guaranteed table by referring to the transmitted information; (AA) Database management server; (BB) Start; (CC) End; (DD) Personal information management server