A study on the color removal by irradiation of ${gamma}-ray$ was carried out to reclaim the secondary effluent for the purpose of industrial water. Coagulation, ozone and ion exchange methods were compared. It could know that irradiation method was the most effective in color removal. The color was removed by 87.5% at 0.5 Mrad and it was increase with dose. High removal efficiency could be obtained in low pH and low concentration of $CO3^{-2}$. This process can be applied to the treatment of secondary effluent and is considered to be one of the most useful tertiary treatment.