A display device includes a substrate and a first pad. The substrate includes a display area to display an image, and a pad area outside the display area. The first pad is in the pad area, and includes first pad terminals extending parallel to one another in a first direction. The first pad terminals include: first connection pad terminals arranged along a first column that forms a first slope angle with the first direction; second connection pad terminals spaced apart from the first connection pad terminals and arranged along a second column that forms a second slope angle with the first direction; and a first dummy pad terminal between a pair of adjacent first connection pad terminals among the first connection pad terminals along the first column. The first dummy pad terminal and the first connection pad terminals are in different layers than one another.