A display device includes a substrate including a display area in which a display element is arranged and a non-display area having a pad area outside the display area, a first thin-film transistor arranged in the display area of the substrate and including a first semiconductor layer and a first gate electrode insulated from the first semiconductor layer, a first voltage line which extends in a first direction on the first gate electrode, a data line apart from the first voltage line and which extends in the first direction, connection lines which connects the data line to a pad in the pad area in the display area, and a conductive layer arranged in a layer between the first voltage line and the data line.