remaining oxidized active species and then sufficiently dried the resulting denim cloth was measured for the total k s the results obtained are shown in the lowermost lines of tables 1 and 2 below the same procedures as in example 1 with the same conditions for the electrification were carried out except that the processing time was changed to 3 and 5 minutes and the total k s was measured the results obtained are shown in table 1 the degree of decolorizing is increased corresponding to the processing time and thus the extent of decolorizing can be easily adjusted by the electrification time the same procedures as in example 1 with the same conditions for the electrification were carried out except that the electric current was changed to 40 and 60 ma and the total k s was measured the results obtained are shown in table 2 the degree of decolorizing is increased corresponding to the electric current and thus the extent of decolorizing can be easily adjusted by the electric current the same procedures as in example 1 with the same conditions for the electrification were carried out except that ion exchanged water and a sodium sulfate solution of 10 g l were used as the solution.