A display device can include a substrate including a display area, on which an input image is displayed, and a pad part including a convex portion and a concave portion that are alternately positioned outside the display area and have a height difference between them, and a circuit element attached to the pad part and including a bump inserted into the concave portion of the pad part. The pad part can further include a lower pad electrode electrically connected to a signal line extended from the display area, a first insulating layer disposed on the lower pad electrode in the convex portion, and an upper pad electrode disposed on the first insulating layer, connected to the lower pad electrode through a first contact hole penetrating the first insulating layer and extending into at least a portion of the concave portion.