[Problem] In guest invitation for a smart lock, a burden on an owner on invitation is reduced and impersonation or invitation of an unintended third party is prevented.
[Solution] A representative guest terminal 102 requesting unlocking of a smart lock 400 generates authentication information referred to at the time of a request for unlocking, imparts a signature to the authentication information, and transmits the authentication information to an owner terminal 101. The owner terminal 101 verifies a signature of the representative guest terminal 102, imparts a signature to the authentication information, and transmits the authentication information to a management server 200. The management server 200 verifies the signatures of the representative guest terminal 102 and the owner terminal 101, stores the owner terminal 101 and the representative guest terminal 102 in association with each other, and stores the authentication information and the representative guest terminal 102 in association with each other. When the management server 200 receives an unlocking request from the smart lock 400 and successfully authenticates the unlocking request by referring to the stored authentication information, the smart lock 400 is unlocked.