A key information management device comprising: an information processing device configured to i) deliver key information to a mobile terminal (20; 20Aa; 20Ab; 20Ac; 20Ad; 20B) as the mobile terminal transmits a predetermined transmission signal toward a vehicle (10; 10A; 10B), the key information being information for unlocking the vehicle, starting the vehicle, or unlocking and starting the vehicle (10; 10A; 10B), and ii) register permission for a user of the vehicle (10; 10A; 10B) to use a predetermined service using the vehicle (10; 10A; 10B), the permission being permission to cause the information processing device to deliver the key information to a third party mobile terminal (20Ac; 20Ad; 20B) of a third party concerned with the predetermined service, other than the user of the vehicle (10; 10A; 10B), as an external device concerned with the predetermined service transmits a predetermined request signal; the key information management device being characterized in that the information processing device is configured to register the permission further in association with unique information corresponding to an owner user of the vehicle (10; 10A; 10B), and to transmit information related to the predetermined service to an owner mobile terminal having the unique information corresponding to the owner user in response to a request from the owner mobile terminal having the unique information corresponding to the owner user; and the predetermined service corresponds to the permission associated with the unique information corresponding to the owner user. an information processing device configured to i) deliver key information to a mobile terminal (20; 20Aa; 20Ab; 20Ac; 20Ad; 20B) as the mobile terminal transmits a predetermined transmission signal toward a vehicle (10; 10A; 10B), the key information being information for unlocking the vehicle, starting the vehicle, or unlocking and starting the vehicle (10; 10A; 10B), and ii) register permission for a user of the vehicle (10; 10A; 10B) to use a predetermined service using the vehicle (10; 10A; 10B), the permission being permission to cause the information processing device to deliver the key information to a third party mobile terminal (20Ac; 20Ad; 20B) of a third party concerned with the predetermined service, other than the user of the vehicle (10; 10A; 10B), as an external device concerned with the predetermined service transmits a predetermined request signal; i) deliver key information to a mobile terminal (20; 20Aa; 20Ab; 20Ac; 20Ad; 20B) as the mobile terminal transmits a predetermined transmission signal toward a vehicle (10; 10A; 10B), the key information being information for unlocking the vehicle, starting the vehicle, or unlocking and starting the vehicle (10; 10A; 10B), and ii) register permission for a user of the vehicle (10; 10A; 10B) to use a predetermined service using the vehicle (10; 10A; 10B), the permission being permission to cause the information processing device to deliver the key information to a third party mobile terminal (20Ac; 20Ad; 20B) of a third party concerned with the predetermined service, other than the user of the vehicle (10; 10A; 10B), as an external device concerned with the predetermined service transmits a predetermined request signal; the key information management device being characterized in that the information processing device is configured to register the permission further in association with unique information corresponding to an owner user of the vehicle (10; 10A; 10B), and to transmit information related to the predetermined service to an owner mobile terminal having the unique information corresponding to the owner user in response to a request from the owner mobile terminal having the unique information corresponding to the owner user; and the predetermined service corresponds to the permission associated with the unique information corresponding to the owner user.