The present invention is directed to a portable display device having at lease two display elements, at least two foldable panel housings for receiving and supporting the display elements circuit boards and other parts, respectively, and optical elements provided on the top surface of the one of the sidewalls of the panel housings and mounted in a joint portion of the display elements, wherein one of the sidewalls of the panel housings are cut to form openings or a connecting joint portion, and the sidewalls of the optical elements is adjacently disposed each other when the panel housings are unfolded. The portable display device allows a single large sized screen, and whereby a joint portion between the two display panels as non-display area may be minimized.