To provide a method for treating anionic organic material-containing waste water having a small amount of generated sludge, without requiring an acid resistant specification for a flocculating sedimentation tank and a pipe from the flocculating sedimentation tank to a resin tower, also having no problem of an outflow of a loaded metal and formation of a hazardous compound, and industrially advantageous.

Copper ions are added to the anionic organic material-containing waste water, and flocculate is separated. Separate water is brought into contact with an ion-exchange resin and/or a chelating resin to remove a remaining copper ion. The ion-exchange resin and/or the chelating resin after contact with the separate water is regenerated. A regenerated waste liquid is used as a copper ion supply source for flocculation treatment of the anionic organic material-containing waste water.