A display device comprising: a display module having a first non-foldable area, a foldable area, and a second non-foldable area, which are arranged in a first direction in an unfolded state; a first support layer disposed under the display module and having a lattice pattern including a plurality of first holes overlapping the foldable area, wherein the first holes are arranged in the first direction and a second direction intersecting the first direction, whereineach of the first holes has a first width in the second direction and a second width in the first direction, wherein the lattice pattern comprises: a pattern portion in which the first holes are defined; and a plurality of extension branches at first and second ends of the lattice pattern opposite to each other in the second direction, arranged in the first direction, and extending in the second direction, characterized in that the first width is in a range from 5,000 μm to 6,000 μm, and the second width is in a range from 125 μm to 175 μm wherein: each of the extension branches extends from two first branches adjacent to each other in the first direction, and a width in the first direction of each extension branch is greater than a third width of the first branch and the second width of the first hole. a display module having a first non-foldable area, a foldable area, and a second non-foldable area, which are arranged in a first direction in an unfolded state; a first support layer disposed under the display module and having a lattice pattern including a plurality of first holes overlapping the foldable area, wherein the first holes are arranged in the first direction and a second direction intersecting the first direction, whereineach of the first holes has a first width in the second direction and a second width in the first direction, wherein the lattice pattern comprises: a pattern portion in which the first holes are defined; and a plurality of extension branches at first and second ends of the lattice pattern opposite to each other in the second direction, arranged in the first direction, and extending in the second direction, characterized in that the first width is in a range from 5,000 μm to 6,000 μm, and the second width is in a range from 125 μm to 175 μm wherein: each of the extension branches extends from two first branches adjacent to each other in the first direction, and a width in the first direction of each extension branch is greater than a third width of the first branch and the second width of the first hole. a pattern portion in which the first holes are defined; and a plurality of extension branches at first and second ends of the lattice pattern opposite to each other in the second direction, arranged in the first direction, and extending in the second direction, characterized in that the first width is in a range from 5,000 μm to 6,000 μm, and the second width is in a range from 125 μm to 175 μm wherein: each of the extension branches extends from two first branches adjacent to each other in the first direction, and a width in the first direction of each extension branch is greater than a third width of the first branch and the second width of the first hole. each of the extension branches extends from two first branches adjacent to each other in the first direction, and a width in the first direction of each extension branch is greater than a third width of the first branch and the second width of the first hole.