A mark issuing server operated by a mark issuer manages mark information collectively. A terminal of a user sends an information providing request to an information providing server of an information provider, and issues a mark issuing request to the mark issuing server on the basis of the information providing request. The information providing server searches for information corresponding to the information providing request from the terminal of the user, and provides the terminal of the user with information including requested information and location information of the mark issuing server. The mark issuing server determines validity of information provided from the information providing server on the basis of the mark issuing request, and sends a mark to the terminal of the user when the validity is verified, and the terminal of the user displays the mark with the information provided from the information providing server.