A thin film transistor substrate including a second electrode connected to a first electrode within a shared contact hole; and a fourth electrode connected to a third electrode within the shared contact hole, wherein the shared contact hole penetrates through a plurality of stacked insulating layers, and wherein an insulating layer below at least one of a connection portion in which the first electrode and the second electrode are connected and a connection portion in which the third electrode and the fourth electrode are connected has an undercut structure within the shared contact hole.