A display device includes: a substrate including a display area, and a peripheral area outside the display area, the display area including a first area and a second area; a data line at the display area; a pad area at the peripheral area; a connection line at the first area, and connected to the data line to transmit a data signal supplied from the pad area to the data line; a voltage line on the substrate; and a dummy line at the second area, and connected to the voltage line, the dummy line including a plurality of horizontal dummy patterns and a plurality of vertical dummy patterns that are alternately connected to one another.