An all-solid-state electrochromic device (SED) employing electrodeposited WO, and prussian blue film with poly(vinyl chloride) (PVC) gel electrolyte that has high conductivity (10(-3) S/cm) at room temperature has been fabricated. The SED has been found to have excellent electrochromism and memory characteristics. A reversible color change between blue and colorless was observed when an appropriate potential was applied repeatedly to the electrochromic display device.