The present disclosure illustrates a signal transmission device and a display device using the same. The signal transmission device includes a first flexible printed circuit board comprising a first circuit layer and a connection member, wherein the first circuit layer is electrically connected to a display module and a system; a second flexible printed circuit board disposed on the first flexible printed circuit board, and comprising a second circuit layer; a third flexible printed circuit board disposed on the first flexible printed circuit board, and comprising a third circuit layer; insulating layers disposed between the first, second and third flexible printed circuit boards, and comprising a plurality of through holes formed thereon in a vertical direction; and conductive pillars disposed in the through holes, respectively, wherein the second and third circuit layer are electrically connected to the system through the first circuit layer and the conductive pillars.