A user terminal device comprising: a flexible display; a hinge configured to asymmetrically fold together the flexible display into a folded state in which an exposed area that is a portion of the flexible display is viewable; and a controller comprising one or more processors (293, 294) configured to: control the flexible display to display a first user interface on the flexible display in an unfolded state in which the flexible display is unfolded; and control the flexible display to display a second user interface which is different from the first user interface on the exposed area of the flexible display in the folded state, and characterized in that the controller is further configured to: control the flexible display to display, as the second user interface, a lock screen on the exposed area of the flexible display in the folded state, detect a touch interaction on the exposed area to release the lock state of the user terminal device, detect an unfolding interaction, and, based on both the detected touch interaction and the detected unfolding interaction, release the lock state and control the flexible display to display, as the first user interface, a home screen on full screen. a flexible display; a hinge configured to asymmetrically fold together the flexible display into a folded state in which an exposed area that is a portion of the flexible display is viewable; and a controller comprising one or more processors (293, 294) configured to: control the flexible display to display a first user interface on the flexible display in an unfolded state in which the flexible display is unfolded; and control the flexible display to display a second user interface which is different from the first user interface on the exposed area of the flexible display in the folded state, and characterized in that the controller is further configured to: control the flexible display to display, as the second user interface, a lock screen on the exposed area of the flexible display in the folded state, detect a touch interaction on the exposed area to release the lock state of the user terminal device, detect an unfolding interaction, and, based on both the detected touch interaction and the detected unfolding interaction, release the lock state and control the flexible display to display, as the first user interface, a home screen on full screen. control the flexible display to display a first user interface on the flexible display in an unfolded state in which the flexible display is unfolded; and control the flexible display to display a second user interface which is different from the first user interface on the exposed area of the flexible display in the folded state, and characterized in that the controller is further configured to: control the flexible display to display, as the second user interface, a lock screen on the exposed area of the flexible display in the folded state, detect a touch interaction on the exposed area to release the lock state of the user terminal device, detect an unfolding interaction, and, based on both the detected touch interaction and the detected unfolding interaction, release the lock state and control the flexible display to display, as the first user interface, a home screen on full screen. control the flexible display to display, as the second user interface, a lock screen on the exposed area of the flexible display in the folded state, detect a touch interaction on the exposed area to release the lock state of the user terminal device, detect an unfolding interaction, and, based on both the detected touch interaction and the detected unfolding interaction, release the lock state and control the flexible display to display, as the first user interface, a home screen on full screen.