To enhance supervision for discharging of water pollutants, the Ministry of Environment has been expanding the number of water pollutants (51 species) and specific hazardous substances (29 species) in legal regulations annually. The present discharging state of water pollutants and specific hazardous substances was investigated and data mining technique as well as statistical analysis were conducted to draw discharging characteristics of water pollutants from the industrial wastewater effluent in incheon area by the industrial category. Upon investigation, 1,1-dichloroethylene, benzene, carbon-tetrachloride, vinylchloride, acrylonitrile, PCP, organic phosphorus, 1,2-dichloromethane, PCE had not ever detected or were detected only once within a investigation period. The 95% tiles of both 1,4-dioxane and CN concentration were 3.409 mg/L and 0.465 mg/L respectively and these values were in less than effluent quality standard for others except clean area. As a result of PCA, principal components of water pollution by industrial wastewater effluent in incheon area consist of PC1, which is associated with both Ni and Zn such as plating facilities, PC2, which is associated with Fe such as metal processing facilities, PC3, which is associated with Cu such as copper rolling and pressing processing facilities, PC4, which is associated with Cr such as Cr discharging facilities. As a result of classification for the industrial category using by SVM, LR, ANN techniques, ANN is the most accurate of algorithms and classification possibility means probability for grasping discharging characteristics of water pollutants from the industrial wastewater effluent in incheon area by the industrial category.