A new all-solid-state electrochromic display device employing prussian blue and WO3 particulate film with a PMMA gel electrolyte has been fabricated. The conductivity of the PMMA gel electrolyte prepared was ca. 10(-3) S/cm at room temperature. A reversible color change between blue and colorless was observed when an appropriate potential was applied repeatedly to the electrochromic display device. When the potential cycling was more than 5000 times, less than 10% of the electrochromic characteristics were lost.