an alkali metal or an ammonium group; and n is an integer of 1 to 100, and (C) an amide compound of perfluoroether carboxylic acid represented by the following general formula: F CF(CF3)CF2 O!pCF(CF3)CONH(CH2 CH2 NH)rH where p is an integer of 1 or more and r is an integer of 1 to 6. 6.