A display device comprising: a substrate including a display area and a non-display area; a plurality of pixels disposed in the display area of the substrate; a plurality of data lines (D1, D2,..., Dm) connected to the plurality of pixels; a semiconductor disposed in the display area of the substrate; a gate electrode overlapping the semiconductor; a source electrode and a drain electrode, each connected to the semiconductor and separated from each other; a crack sensing line connected to at least one of the plurality of data lines (D1, D2,..., Dm), the crack sensing line disposed in the non-display area of the substrate; and a dummy pattern layer connected to the crack sensing line; and wherein the dummy pattern layer has a higher resistance than the crack sensing line, the display device further comprising: a connection electrode at least partially overlapping each of the crack sensing line and the dummy pattern layer, wherein the crack sensing line and the dummy pattern layer are connected to each other by the connection electrode, the crack sensing line is made of the same material as the gate electrode, the dummy pattern layer is made of the same material as the semiconductor, and the connection electrode is made of the same material as the plurality of data lines (D1, D2,...), the display device further comprising a common voltage line (ELVSS) disposed in the non-display area of the substrate, adjacent to both the crack sensing line and the dummy pattern layer, wherein the crack sensing line and the dummy pattern layer each extend in parallel with the common voltage line (ELVSS). a substrate including a display area and a non-display area; a plurality of pixels disposed in the display area of the substrate; a plurality of data lines (D1, D2,..., Dm) connected to the plurality of pixels; a semiconductor disposed in the display area of the substrate; a gate electrode overlapping the semiconductor; a source electrode and a drain electrode, each connected to the semiconductor and separated from each other; a crack sensing line connected to at least one of the plurality of data lines (D1, D2,..., Dm), the crack sensing line disposed in the non-display area of the substrate; and a dummy pattern layer connected to the crack sensing line; and wherein the dummy pattern layer has a higher resistance than the crack sensing line, the display device further comprising: a connection electrode at least partially overlapping each of the crack sensing line and the dummy pattern layer, wherein the crack sensing line and the dummy pattern layer are connected to each other by the connection electrode, the crack sensing line is made of the same material as the gate electrode, the dummy pattern layer is made of the same material as the semiconductor, and the connection electrode is made of the same material as the plurality of data lines (D1, D2,...), the display device further comprising a common voltage line (ELVSS) disposed in the non-display area of the substrate, adjacent to both the crack sensing line and the dummy pattern layer, wherein the crack sensing line and the dummy pattern layer each extend in parallel with the common voltage line (ELVSS). a connection electrode at least partially overlapping each of the crack sensing line and the dummy pattern layer, wherein the crack sensing line and the dummy pattern layer are connected to each other by the connection electrode, the crack sensing line is made of the same material as the gate electrode, the dummy pattern layer is made of the same material as the semiconductor, and the connection electrode is made of the same material as the plurality of data lines (D1, D2,...), the display device further comprising a common voltage line (ELVSS) disposed in the non-display area of the substrate, adjacent to both the crack sensing line and the dummy pattern layer, wherein the crack sensing line and the dummy pattern layer each extend in parallel with the common voltage line (ELVSS).