The present invention relates to cloud service supporting technology. Particularly, a cloud service system based on an enhanced security function includes a terminal that includes a trusted platform therein and is configured to perform security authentication based on encrypted information provided by the trusted platform, to perform normal authentication based on preregistered ID and password information, and to use a cloud service according to the security authentication and the normal authentication, and a cloud service apparatus that is configured to provide the cloud service to the terminal after completing the security authentication and the normal authentication with the terminal that includes the trusted platform therein. The service apparatus, the terminal, and a method for supporting them are also disclosed.