A cover window including a flat portion and a curved portion extending from an end of the flat portion. The curved portion of the cover window includes a first section, a second section, and a third section, where the second section is disposed between the first section and the third section, an inner surface of the cover window contacts with an adhesive layer, a first radius of curvature having an average value of a radius of curvature of the inner surface of the cover window in the first section is greater than a second radius of curvature having an average value of a radius of curvature in the second section, and a third radius of curvature having an average value of a radius of curvature of the inner surface of the cover window in the third section is greater than the second radius of curvature.