Electrochromic (EC) phenomena are that their optical transmittance and/or reflectance change because of chemical reduction/oxidation processes occurred by the ions insertion and extraction when a potential is externally applied. In order to increase the ratio and speed of chemical reduction/oxidation processes, which are essential required property, there are many efforts to prepare the ionic conductors based on such as organic-solvents/liquids, ionic liquids, and polymer/gel. Although organic-solvent/liquid based ion conductors show better physical properties likely lower viscosity, density, and melting point helps easier ion mobility in medium, they exhibit low stability, high flammability, and low safety which limit the promising wide range application of EC devices (ECDs). Therefore instead of using organic-solvent/liquid based ion conductors, ionic liquids (ILs) are considered because of non-volatility, possibly makes choice and/or certainly increasing ion concentration, etc. In spite of these advantages, polymer and/or gel-typed ion conductors are only suitable in terms of the flexibility and scalability of ECDs. As their visco-elastic properties, polymer/gel-based ion conductors afford guaranteed good contact with the electrodes, and they also have simple processablity resulted in low production cost and better mechanical properties along with improved stability, reliability, and safety. Therefore, in the present work, polymer-based ion conductor is prepared and is optimized in order to obtain the efficient contrast ratio and switching speed for ECDs. In order to see the feasibility, the operation of polymer-based ion conductor introduced ECD fabricated on flexible substrate will be also presented. Acknowledgement This work was supported by Institute for Information & communications Technology Promotion (IITP) grant funded by the Korea government (MSIP) (B0101-16-0133, The core technology development of light and space adaptable energy-saving I/O platform for future advertising service).