An authentication broker apparatus includes an extracting unit and a transmitting unit. In response to an authentication request from a service providing apparatus that provides a service, the extracting unit extracts, from identification managing apparatuses that manage user ID codes used by users to access a service, at least one ID managing apparatus that fulfills an authentication condition relating to authentication of the service providing apparatus that has requested authentication. The transmitting unit transmits, to the service providing apparatus, link information to access the at least one ID managing apparatus extracted by the extracting unit.