A portable display device is provided in which two display panels are joined to each other to form a single screen when two panel housings are unfolded from a folded state. The portable display device includes at least two panel housings and display panels that are mounted on the panel housings, respectively. When the panel housings are unfolded, the display panels are joined to each other to form a single screen. The distance between the display panels when the display panels are contiguous to each other is less than 3 mm and the distance between input units or between input sensors is less than 3 mm.