The effect of O-3 treatment and AOP (Advanced Oxidation Processes) treatment on the decomposition of endocrine disruptors were investigated by using continuous type pilot plant. Reaction kinetic evaluations of these processes were also carried out. In this study, the endocrine disruptors were classified into 2 groups: (1) DXNs: dioxins and (2) EDs: endocrine disruptors other than dioxins. For the case of DXNs decomposition, highly concentrated DXNs in a incinerator washwater were degraded by UV/O-3 combined treatment. Influence of O-3 dosage and forms of DXNs on the reaction rate constant were evaluated. The incinerator washwater was sampled from a scrubber, which was used for the flue gas treatment of a garbage incinerator facility. For the case of EDs decomposition, the effect Of O-3 dosage on the reaction rate constant were investigated during O-3 treatment of secondary treated sewage. Also, a comparison was made on the degradability for the above 2 groups. The following results were obtained. (1) The DXNs contained in the incinerator washwater had different decomposition properties depending on the particle size of suspended solid. Above a particle size of 1.0 mum, the reaction rate constant was relatively small and the DXNs were relatively non-degradable. On the other hand, when suspended solid particle size was below 1.0 mum, the reaction rate constant was large and the DXNs were relatively degradable. (2) The amount of decomposed DXNs per consumed O-3 increased with the increase of DXNs concentrations in the influent and higher DXNs decomposition efficiencies were obtained. (3) The reaction rate constant in the EDs decomposition was larger than that in the DXNs decomposition, and the EDs were found to be relatively easy to be decomposed. Once DXNs on the suspended solid particle size larger than 1.0 mum in the incinerator washwater were non-degradable, we found that they should be filtered and concentrated separately prior to the AOP treatment to ensure an efficient treatment.