A cover window, a manufacturing method of a cover window, and a display device including a cover window are provided. A cover window includes a folding portion and a non-folding portion, and the folding portion includes an inside surface that is compressed when folded and an outside surface that is stretched when folded, the folding portion includes a first layer adjacent to the outside surface, a second layer adjacent to the inside surface, and a third layer between the first layer and the second layer, the folding portion and the non-folding portion include at least one metal ion, a concentration of the metal ion included in the second layer is higher than a concentration of the metal ion included in the first layer, and the first layer includes a plurality of depletion regions.