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 (A) a non-crystalline fluorine-containing polymer having, in a trunk chain and/or side chain of the polymer molecule, a structural unit D having five or more chained units derived from a fluorine-containing ether, (B) an electrolytic compound and (C) a solvent, and 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. The electrolyte is useful for various electrochemical devices.