A 2D/3D display device is provided. The 2D/3D display device includes a flat display device and a parallax barrier panel disposed on a display surface of the flat display device. The parallax barrier panel has a barrier pattern which includes a first electrochromic material layer and a second electrochromic material layer. In a 2D display mode, the barrier pattern, the first electrochromic material layer, and the second electrochromic material layer are transparent. In a 3D stereoscopic display mode, the barrier pattern is non-transmissible. The first electrochromic material layer has a first color, and the second electrochromic material layer has a second color.