A method for the decolorization of waste water containing coloring matters comprising dyestuff and/or pigment, in which PVA is added to a waste water containing coloring matters as above mentioned so as to catch the coloring matters in the waste water into the PVA, a precipitant of the coloring matters is added to the resultant waste water so as to render the coloring matters absorbed onto the PVA insoluble, a coagulant of PVA is added to the waste water so as to make the PVA insoluble, and then the thus insolubilized PVA containing the coloring matters is separated for the recovery thereof, and thus the decolorization of a waste water containing the coloring matters can be done skillfully and economically by eliminating the drawbacks in the conventional arts.