To retrieve and view additional information added not only to an original content but also to individual contents by the other user by adding additional information to the displayed content and managing inputted additional information while associating it with the additional content.

A package part 140 generates display data in a prescribed format in accordance with a content identifier and an annotation identifier, which are transferred from a content management part 110 and an annotation management part 130. A retrieval result display part 172 displays a retrieval result based on display data. When the display of the content is instructed, the contents and the content of the annotation are transferred from the content management part 110 and the annotation management part 130 to a content display part 171 and they are displayed. When the annotation is inputted to the content, the annotation input part 160 stores the inputted annotation in a data base server.