A user terminal device includes: a flexible display that is divided into a main area, which is disposed on a front surface, and a sub area, which includes a bent portion extending from the main area toward a side surface; a touch sensor configured to receive a touch input of a user in at least one of the main area and the sub area; and a controller configured to, in response to a predetermined event occurring, control the flexible display to display, in the main area, a plurality of user interface (UI) elements, and in response to one of the plurality of UI elements displayed in the main area being selected, control the flexible display to display the selected UI element in the sub area.