Effective utilization of a database while protecting a data provider's privacy is accomplished by an access control system which controls access to a database in which open information and secret information about a data provider are stored while being related to each other has an output request acquisition section which obtains an output request for output of information generated by accessing the database, a plural-term output authorization section which prohibits output of information generated by combining the open information and the secret information in output information requested to be output according to the output request, and which permits output of information generated by using the secret information without using the open information, and an output section which outputs the information in the output information permitted by the plural-term output authorization section to be output.