The effects of polymer gel electrolyte on the photoelectric and driving characteristics of Prussian blue (PB)-based electrochromic (EC) cells were systematically investigated under different preparation conditions. The EC cells were switched from the coloring to decoloring mode by applying ±1.5 V. Subsequently, we prepared an automatic driving circuit wherein the signal of the voltage was alternately applied. The thickness of the PB layer significantly depended on the switching speed as opposed to the electrolyte concentration and the polymer gel electrolyte. In particular, the speed of coloring exceeds that of decoloring due to the electron exchange in the chemical reaction. The speed varied from approximately 5 to 10 times based on the type of the electrolyte.