A display device includes a main body configured to have a display module to which a user interface is output, a bending module located at a center of a back surface of the main body, and a controller. The controller controls the bending module to change a curvature of the display module to any one of a flat mode in which the display module is flat, a first bending mode in which the display module has a first curvature, and a second bending mode in which the display module has a second curvature, wherein the second curvature is a maximum curvature of the display module. Then, the controller changes at least one of a size and a position of a display region to which the user interface is output, according to whether a mode is the flat mode, the first bending mode, or the second bending mode.