NOVELTY - An ionic group-containing aromatic polyether copolymer comprises ionic group-containing aromatic polyether copolymer (B1)-(B3), carbonyl group-containing compound (D1) and benzophenone-type compound (A1). The sum total content of ionic group-containing aromatic polyether copolymer, carbonyl group-containing compound and benzophenone-type compound is 100 mol%. The content of the ionic group-containing aromatic polyether copolymer and carbonyl group-containing compound is 10-52 mol% and 35-52 mol%, respectively.    USE - Ionic group-containing aromatic polyether copolymer is used for polymer electrolyte material for polymer electrolyte molding, polymer electrolyte composite film and polymer electrolyte fuel cell (all claimed). Uses include but are not limited to power supply of mobile telephone, personal computer, television, radio, truck, game machine, motor vehicle, electric power-assisted bicycle, music player, personal digital assistant, etc.    ADVANTAGE - The polymer electrolyte material is efficiently prepared, using the ionic group-containing aromatic polyether copolymer. The polymer electrolyte fuel cell obtained by the polymer electrolyte material has high capacity, fuel shut off property, mechanical strength, hot water-resistant property, heat-resistant methanol property, workability, proton conductivity and durability for a long period of time.    DETAILED DESCRIPTION - An ionic group-containing aromatic polyether copolymer comprises ionic group-containing aromatic polyether copolymer of formulae (B1)-(B3), carbonyl group-containing compound of formula (D1) and benzophenone-type compound of formula (A1). The sum total content of ionic group-containing aromatic polyether copolymer, carbonyl group-containing compound and benzophenone-type compound is 100 mol%. The content of the ionic group-containing aromatic polyether copolymer and carbonyl group-containing compound is 10-52 mol% and 35-52 mol%, respectively.    Y'=ionic group.    INDEPENDENT CLAIMS are included for the following:    (1) polymer electrolyte material, which contains ionic group-containing aromatic polyether copolymer;    (2) polymer electrolyte molding, which contains polymer electrolyte material; and    (3) polymer electrolyte composite film, which has porous membrane filled with polymer electrolyte material. The porous membrane is polypropylene, polyolefin or fluorine-type microporous film.