ELECTRONIC KEY REGISTRATION SYSTEM

An electronic key registration system includes an electronic key (2) and a communication master (14). The electronic key (2) transmits a registration code. The communication master (14) receives the registration code from the electronic key (2), obtains key information using the registration code, and registers the key information. The registration code is set in accordance with the communication master (14) to which the electronic key (2) is registered. The communication master (14) includes a level determination unit (17), which determines a key registration security level when the electronic key (2) is registered to the communication master (14), and a registration execution unit (22), which obtains the key information using the registration code based on the determined key registration security level and registers the key information to the communication master (14).