Reversible electrochromic mirror by electroplating and electrodissolution of Ag film has been investigated onto transparent ITO electrode. It’s applicable to smart window and thermal management for house and vehicle. In order to form mirror surface of Ag film, Pd nanoparticles were firstly deposited onto ITO electrode by chronopotentiometry at the constant current of -10 mA/cm² for 0.5 s, resulting in the diameter of Pd nanoparticles of 63 nm and good dispersion from SEM observation and visible light transmittance of around 80 % from UV–vis absorption spectroscopy. Pd nanoparticles are electrochemically stable for electroplating and electrodissolution of Ag film and behave as catalyst for forming Ag film. Without Pd nanoparticles on ITO electrode, the deposited Ag film becomes white surface because of light scattering from less dispersive and quite large Ag semi sphere crystals on the ITO electrode. However, Ag mirror surface was not formed even on the Pd nanoparticle deposited ITO electrode. So, several additive regents were investigated to form Ag mirror surface. At first, as 2-hydroxypyridine (2-HP) is employed as additive, yellow color smooth Ag mirror surface was achieved at the electroplating condition of the constant current of -4 mA/cm² for 100 s. The SEM observation indicates that Ag crystal grew up anisotropically to form planar crystal. On the other hand, eletrodissolution of Ag film at the constant current of +1 mA/cm² for 400 s was imperfect to remain residue onto ITO electrode and the color of the Ag plating solution changed from transparent to brown due to the oxidation of 2-HP. Next, as citric acid was used as additive, smooth Ag mirror surface was created by the electroplating condition of the constant current of -4 mA/cm² for 20 s. The SEM observation shows anisotropical Ag crystal growth as similar as that in the 2-HP additive. The time taking to form Ag mirror state becomes shorter than that in the 2-HP additive because the anisotropy ratio of citric acid would be larger than that of 2-HP. The electrodissolution of Ag film at the constant current of +4mA/cm² for 20 s shows that it’s almost back to the transparent ITO electrode at the transmittance of ca. 70 %. Repeating property has been tried to be several times so far. We will determine the repeating limit in this system.