Polymeric solid electrolyte having high ionic conductivity about 10^-5 S/cm is applied to construct all solid state WO₃-PB based electrochromic device (ECD). Poly [oligo (oxyethylene) methacrylate]/LiClO₄ hybrid thin film is prepared and sandwiched between WO₃ and PB coated ITO glass electrodes in a dry argon atmosphere. The increase of the applied voltage from 1 to 3 V results in the increase of an optical density change in coloring and bleaching processes for this ECD. Optical density change is about 50% larger than that for WO₃ based ECD. Furthermore, the charges can be injected 3 times more than that for WO₃ based ECD. The optical density at 800nm for this ECD is proportional to the injected charges. These results suggest that PB electrode acts as effective cation supplying or accepting electrode for WO₃ as well as coloring layer, because it shows opposite redox behavior against WO₃. Cycling of coloring and bleaching is carried out for more than several hundred times without any decay in the activity and efficiency.