Solid Polymer Electrolyte (SPE) has great potential in replacing liquid electrolytes. The SPE has many advantages such as high thermal stability, good flexibility, and non-flammable. One of the polymers that can be used is chitosan biopolymer from shrimp skin extraction. Generally, polymers are isolators and have low ionic conductivity, so that modification to the structure of chitosan is needed to increase the ionic conductivity. One way to modify the chitosan structure is by plasticizer addition. In this study the addition of sorbitol plasticizer was carried out with a variation between 0, 20, 40, 60 and 80 (in weight percent) which is called as CA for pure chitosan, CA1, CA2, CA3, CA4 and CA5 respectively. The synthesis of chitosan electrolyte film was prepared by casting method. Then qualitative and quantitative analysis was carried out by using X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and mechanical properties. Optimal composition was obtained by 40% (in weight percent) sorbitol addition with a conductivity of 3.74 ´ 10 -5 S.cm -1 . XRD measurement shows more amorphous polymers with more sorbitol addition. The sorbitol addition also increases the tensile strength, elongation and Young modulus of film flexibility become 52.3%, and 158.3MPa and 19.8MPa, respectively.