Disclosed herein is a device authentication system capable of authenticating devices efficiently using the common key system. When a CE device requests service offerings from a service server, the service server in turn requests the CE device to be authenticated by a device authentication server. Given the request, the CE device causes the device authentication server to perform device authentication on that device and transmits the result of the device authentication to the service server. Upon receipt of the device authentication result from the CE device, the service server causes the device authentication server to check that the authentication has been performed correctly and then starts offering services to the CE device. The CE device and device authentication server share a pass phrase, and each of the two parties checks that the other party indeed retains the pass phrase for mutual authentication.