A home domain building method and system that allow devices to join a home domain using smart cards. In the method, a master device reads device information from a smart card having a device ID and a device key as the device information of a guest device authenticated as a legal device and transmits a challenge request signal to the guest device, the guest device randomly generates a challenge value in response to the challenge request signal, the master device encrypts the challenge value using the device key of the guest device and transmits the encrypted challenge value to the guest device, the guest device decrypts the encrypted challenge value, and if the decrypted challenge value is the same as the challenge value generated in response to the challenge request signal, the guest device allows the master device to join the guest device in the home domain.