A cover window (100, 100A) for a flexible display device, the cover window (100, 100A) comprising: a base substrate that includes an out-folding area (0F1, 0F2), an in-folding area (IF1, IF2), and a plurality of adjacent areas each disposed on opposing sides of at least one of the out-folding area (0F1, 0F2) and the in-folding area (IF1, IF2); a first hard coating layer directly disposed on a top surface of the base substrate, the first hard coating layer having a substantially uniform thickness; and a second hard coating layer directly disposed on a bottom surface of the base substrate opposite to the top surface, the second hard coating layer having a thickness that is different from the thickness of the first hard coating layer, a thickness of a first area (Al) of the second hard coating layer that overlaps with the out-folding area (0F1, 0F2) and the in-folding area (IF1, IF2) of the base substrate is less than a thickness of a second area of the second hard coating layer that overlaps with the adjacent areas of the base substrate thus enabling a reduction in the radius of curvature of the folding areas in a folded state of the cover window, wherein the cover window (100, 100A) is adapted to be disposed on a light emitting surface of a flexible display panel of a flexible display device, wherein the base substrate is adapted to protect the flexible display panel, and wherein a sum of a thickness of the first hard coating layer and a thickness of the second area of the second hard coating layer is larger than a predetermined thickness wherein the out-folding area (OF1, OF2) of the base substrate corresponds to a folding area where in a folded state of the cover window, the portions of the second hard coating layer in the areas adjacent to the out-folding area are closer to each other than the portions of the first hard coating layer in the adjacent areas, and wherein the in-folding area (IF1, IF2) of the base substrate corresponds to a folding area where in a folded state of the cover window, the portions of the first hard coating layer in the areas adjacent to the in-folding area are closer to each other than the portions of the second hard coating layer in the adjacent areas. a base substrate that includes an out-folding area (0F1, 0F2), an in-folding area (IF1, IF2), and a plurality of adjacent areas each disposed on opposing sides of at least one of the out-folding area (0F1, 0F2) and the in-folding area (IF1, IF2); a first hard coating layer directly disposed on a top surface of the base substrate, the first hard coating layer having a substantially uniform thickness; and a second hard coating layer directly disposed on a bottom surface of the base substrate opposite to the top surface, the second hard coating layer having a thickness that is different from the thickness of the first hard coating layer, a thickness of a first area (Al) of the second hard coating layer that overlaps with the out-folding area (0F1, 0F2) and the in-folding area (IF1, IF2) of the base substrate is less than a thickness of a second area of the second hard coating layer that overlaps with the adjacent areas of the base substrate thus enabling a reduction in the radius of curvature of the folding areas in a folded state of the cover window, wherein the cover window (100, 100A) is adapted to be disposed on a light emitting surface of a flexible display panel of a flexible display device, wherein the base substrate is adapted to protect the flexible display panel, and wherein a sum of a thickness of the first hard coating layer and a thickness of the second area of the second hard coating layer is larger than a predetermined thickness wherein the out-folding area (OF1, OF2) of the base substrate corresponds to a folding area where in a folded state of the cover window, the portions of the second hard coating layer in the areas adjacent to the out-folding area are closer to each other than the portions of the first hard coating layer in the adjacent areas, and wherein the in-folding area (IF1, IF2) of the base substrate corresponds to a folding area where in a folded state of the cover window, the portions of the first hard coating layer in the areas adjacent to the in-folding area are closer to each other than the portions of the second hard coating layer in the adjacent areas.