A smart glass uses a guided self-assembled photonic crystal, including a photonic crystal layer that is interposed between a pair of conductive glass plates. The smart glass includes a first material and a second material having a different refractive index from the first material and surrounding the first material. Thereby, the smart glass has a color, even when a dye is not included, by strongly reflecting light in a specific wavelength range incident to the photonic crystal layer. This is because the first material is formed regularly to have a constant distance by guided self-assembly, and the smart glass thereby may obtain a target color by randomly adjusting the distance between the first materials.