A display device includes a substrate including a display area, a peripheral area, and a pad area, first and second voltage lines, and an island dam. The first voltage line is disposed between a first side of the display area and the pad area, the second voltage line is disposed at other sides of the display area, and the island dam is disposed between the display area and the pad area. The first voltage line includes a first main voltage line, and a first connection unit that protrudes from the first main voltage line and extends toward the pad area. The second voltage line includes a second main voltage line, and a second connection unit that protrudes from an end of the second main voltage line and extends toward the pad area. The island dam extends substantially parallel to the first main voltage line.