In a printing service system for providing a service only to authenticated users by receiving authentication information from the users, authentication information issued by a service provider other than a provider of the printing service can be used. When a user who has not registered with the printing service system but has registered with a collaborating service provider uses the printing service, authentication information issued by the collaborating service provider is input from a personal computer to authentication means. The authentication means asks a system of the collaborating service provider about the authentication information and obtains information of affirmation or denial of the authentication information. Based on this result, the authentication means judges whether or not the user accessing the printing service system can receive the service. If the user is eligible for the service, the authentication means notifies printing service means of eligibility of the user for the service, and the printing service means provides the service to the user. If the user is not eligible for the service, the authentication means displays ineligibility of the user on the personal computer.
