Electronic key registration method and electronic key registration system

An electronic key registration system comprising

• a first controller that can be installed in a communication subject and has a first controller ID;
• a second controller that can be installed in the communication subject in lieu of the first controller and has a second controller ID;
• an electronic key including a first memory that is configured to store a unique electronic key ID and an encryption code associated with the electronic key ID, wherein the encryption code is used for encrypted communication between the electronic key and the controller;
• and
• a management center capable of communicating with the first and second controllers, wherein
• the first and second controllers each include a second memory and are each configured to register the electronic key by storing the electronic key ID and the encryption code in the second memory, and
• the management center includes a database and is configured to associate a communication subject ID, which is unique to the communication subject, to the first or second controller ID and the electronic key ID in the database, and
• the management center further includes a registration control unit that is configured to permit reregistration of the electronic key to the second controller when the second controller is installed in the communication subject in lieu of the first controller if the electronic key ID is associated with the first controller ID.