Presently, the treatment process is 2nd treatment system as a biological activated sludge, which is able to treat only organic meterials and suspended solids, and is unable to remove nitrogen and phosphoric compounds. Like this case, in this paper, the removal of nutritive materials in low concentrated synthetic waste-water which corresponds to municipal sewage studied by anaerobic -anoxic-oxic pilot plant(A2/O process). The results obtained are as follows. 1) Presently, the removal of nutritive materials such as nitrogen and phosphoric compounds is impossible, but throughout this study, the possibility of the removal of nutritive materials is found by the A2/O process. 2) In this experimental study, the removal efficiency is as follows, BOD 84%, COD 80%, T-N 77.0% and T-D 83%. 3) This results, if the present municipal waste water treatment -system is a little modified, the removal-problems of nutritive materials such as nitrogen and phosphoric compounds is possible.