A user authentication manager performs user authentication based on user identification information and password stored in an organization-definition-information storage section, in accordance with a log-in request from a user terminal. An organization's portal generator acquires an organization of a user, based on personal organization information stored in the organization-definition-information storage section. The organization's portal generator acquires address information of the organization of the user, from the address information of the organization content stored in the organization-definition-information storage section, and provides a user terminal with Web contents. The navigation generator generates navigation generating information regarding the hierarchical structure stored in the organization-definition-information storage section.