A mobile device includes a user interface including a display panel to display a menu image and a touch panel to receive a password, a network interface to detect an external device, a functional unit to sense a motion of the mobile device and to photograph a user, and a control unit to control the user interface, the network interface, the memory, and the functional unit, to unlock the mobile device according to a user identification process of identifying an authorized user, when the mobile device is in a time condition, in response to the sensed motion, and to unlock the mobile device according to the password when the mobile device is not in the time condition, in response to the sensed motion.