A portable device , comprising: a display unit configured to display an execution screen of an application; a control button receiving a control input corresponding to a press or touch input and comprising a single sensor or two sensors configured to perform a fingerprint recognition function and a control input detection function by either the single sensor or by the two sensors, respectively; and a controller configured to control the display unit and the control button and configured to execute an execution function according to the control input, wherein the controller is further configured to: recognize a fingerprint by activating the fingerprint recognition function for a security authentication when the control button receives the control input inputted by a finger of a user, deactivate the control input detection function when the fingerprint recognition function is activated for the security authentication, and activate the control input detection function when the activated fingerprint recognition function is terminated, characterized in that the controller is further configured to: display a soft button for terminating the fingerprint recognition function in the display unit when the fingerprint recognition function is activated, and terminate the fingerprint recognition function when a touch input on the soft button is detected. a display unit configured to display an execution screen of an application; a control button receiving a control input corresponding to a press or touch input and comprising a single sensor or two sensors configured to perform a fingerprint recognition function and a control input detection function by either the single sensor or by the two sensors, respectively; and a controller configured to control the display unit and the control button and configured to execute an execution function according to the control input, wherein the controller is further configured to: recognize a fingerprint by activating the fingerprint recognition function for a security authentication when the control button receives the control input inputted by a finger of a user, deactivate the control input detection function when the fingerprint recognition function is activated for the security authentication, and activate the control input detection function when the activated fingerprint recognition function is terminated, recognize a fingerprint by activating the fingerprint recognition function for a security authentication when the control button receives the control input inputted by a finger of a user, deactivate the control input detection function when the fingerprint recognition function is activated for the security authentication, and activate the control input detection function when the activated fingerprint recognition function is terminated, characterized in that the controller is further configured to: display a soft button for terminating the fingerprint recognition function in the display unit when the fingerprint recognition function is activated, and terminate the fingerprint recognition function when a touch input on the soft button is detected. display a soft button for terminating the fingerprint recognition function in the display unit when the fingerprint recognition function is activated, and terminate the fingerprint recognition function when a touch input on the soft button is detected. <EOS>