Disclosed are a display unit, a display panel, a display device and an optical information storage device. The display unit comprises a photochromic thin film and an optical filter thin film on a side of the photochromic thin film. The photochromic thin film presents a colored state under an irradiation of a first preset light, and presents a transparent state under an irradiation of a second preset light. A wavelength range of the first preset light is different from that of the second preset light. The optical filter thin film is a one-way optical filter thin film that is substantially transparent to lights coming from a photochromic thin film side, and functions as an optical filter to lights coming from a side opposite the photochromic side to allow the first preset light to pass through and to reflect lights of other wavelengths.