This study was performed to examine factors affecting the decompostion of nondegradable polluants(trichloroethylene(TCE), phenol) using ultrasonic irradiation. The TCE and phenol, which are major hazard compounds causing environmental pollution, were not decomposable pollutants by conventional treatment. The results show that the oxidation and reduction reaction of ultrasound produced $H_2O_2$, $H^+$ and $OH^-$ radical, which decomposed pollutants of TCE and phenol in water. It was confirmed that the ultrasonic irradiation showed an excellent removal efficiency for the nondegradable pollutants than any other processes, utilized in the treatment of organic compounds in the industrial wastewater. Conclusively, these results suggest that ultrasonic irradiation may be highly useful for the treatment of wastewaters contaminated organic pollutants, which is difficult to treat economically by conventional process.