A manufacturing method of a display device includes: loading, on a stage, a panel assembly including: a display panel drivable to display an image, and first and second printed circuit boards attached to the display panel, end portions of the first and second printed circuit boards overlapping each other; providing a jet of air to the overlapping end portion of the second printed circuit board to raise the overlapping end portion away from and expose the end portion of the first printed circuit board; fixing the raised end portion away from the exposed end portion of the first printed circuit board; pre-processing the exposed end portion of the first printed circuit board; and aligning a distal end of the pre-processed end portion of the first printed circuit board and a distal end of the end portion of the second printed circuit board.