NOVELTY - The organic wastewater is subjected to bacteria processing in treatment tank (I) by oxygen aeration in absence of protozoa. Organic substance is decomposed and converted into cohesionless bacteria. The wastewater is subjected to cohesive bacteria processing in absence of cohesionless protozoa in treatment tank (II) to remove cohesionless bacteria by cohesive protozoa. Water quality in tank (I) is temporarily measured. Introduction of wastewater is halted and seed sludge or microorganism formulation is added, when change in water quality is detected.    USE - The method is useful for processing organic wastewater.    ADVANTAGE - The method enables effective and stable processing of organic wastewater even with respect to fluctuation in organic pollutant concentration and suppression of generation amount of surplus sludge.    DETAILED DESCRIPTION - The organic wastewater containing organic pollutant is introduced to treatment tank (I) and bacteria processing is carried out by oxygen aeration, in the absence of protozoa. The organic substance contained in the wastewater is decomposed by oxidation and converted into cohesionless bacteria. The wastewater containing cohesionless bacteria is introduced from tank (I) to treatment tank (II) in which an activated sludge exits. Cohesive bacteria processing is carried out in the absence of cohesionless protozoa and predation removal of cohesionless bacteria is carried out by the cohesive protozoa. The quality of water in treatment tank (I) is temporarily measured. The introduction of wastewater is halted and seed sludge or microorganism formulation is added, when change in water quality, which results in bacteria processing deterioration, is detected. Subsequently, oxygen aeration of tank (I) is performed and introduction of wastewater to tank (I) is restarted.    An INDEPENDENT CLAIM is included for processing apparatus of organic wastewater.    DESCRIPTION OF DRAWING(S) - The figure shows the processing of organic wastewater. (Drawing includes non-English language text)