A method of supporting a login for a web service of a user terminal using a portable device, the method comprising: registering the portable device through a wireless communication with the portable device; encrypting login information for at least one web service and transmitting the encrypted login information to the registered portable device; establishing a communication session with a server of the web service; determining whether the portable device transfers login information to the server of the web service without intervening the user terminal or the portable device transfers the login information to the server of the web service through the user terminal; transmitting a request message requesting a transmission of the login information of the web service to the portable device wherein the request message includes a service identification, ID, identifying the web service; if the portable device is determined to transfer the login information to the server of the web service through the user terminal, after transmitting the request message, receiving from the portable device encrypted login information corresponding to the service ID in response to the request message, decrypting the received login information; and transmitting the decrypted login information to the server of the web service, wherein the request message does not include login uniform resource locator, URL, information of the web service, and a session ID of the established communication session, if the portable device is determined to transfer the login information to the server of the web service through the user terminal, and wherein the request message further includes the login URL information of the web service and the session ID of the established communication session if the portable device is determined to transfer the login information to the server of the web service without intervening the user terminal. registering the portable device through a wireless communication with the portable device; encrypting login information for at least one web service and transmitting the encrypted login information to the registered portable device; establishing a communication session with a server of the web service; determining whether the portable device transfers login information to the server of the web service without intervening the user terminal or the portable device transfers the login information to the server of the web service through the user terminal; transmitting a request message requesting a transmission of the login information of the web service to the portable device wherein the request message includes a service identification, ID, identifying the web service; if the portable device is determined to transfer the login information to the server of the web service through the user terminal, after transmitting the request message, receiving from the portable device encrypted login information corresponding to the service ID in response to the request message, decrypting the received login information; and transmitting the decrypted login information to the server of the web service, wherein the request message does not include login uniform resource locator, URL, information of the web service, and a session ID of the established communication session, if the portable device is determined to transfer the login information to the server of the web service through the user terminal, and wherein the request message further includes the login URL information of the web service and the session ID of the established communication session if the portable device is determined to transfer the login information to the server of the web service without intervening the user terminal.