There is provided a fluorine-containing polymer solid electrolyte which has an excellent ion-conducting property, is high in oxidation resistance, is stable electrochemically and thermally, has sufficient strength and is applicable to various electrochemical devices. The electrolyte comprises (I) a non-crystalline fluorine-containing polymer which has a polar nonionic functional group and has, in a side chain of the polymer molecule, a structural unit D having 1 to 4 units derived from a fluorine-containing ether in the form of continuous chain, (II) an electrolytic compound and as case demands, (III) a solvent. The electrolyte has an ionic conductivity of from 10.sup.-10 to 10.sup.1 S/cm measured at 25.degree. C. by an alternating current complex impedance method, and is useful for various electrochemical devices.