The development of information and communication technology (ICT) has opened the era of the Internet of Things (IoT), in which many devices can connect to the Internet to communicate. Recently, various technologies, such as smart grids, connected cars, and smart farms, have emerged based on IoT, and there is also the smart home, which is the fastest growing market. The smart home is where devices installed for various purposes connect to each other through the Internet so that users can use the service anytime and anywhere. However, while the smart home provides convenience to users, recently the smart home has been exposed to various security threats, such as vulnerability of session/cookies and the use of vulnerable OAuth. In addition, attacks on smart homes by hackers using these vulnerabilities are also increasing. Therefore, in this paper, we propose a user authentication method using the JSON Web Token (JWT) and International Mobile Equipment Identity (IMEI) in the smart home, and solved the problem of unauthorized smart home device registration of hackers by the application of IMEI and JWT technology.