Because the wastewater after cleaning the highway tunnel is enormously generated at once, it is thought that the water pollution shock load would be enlarged as discharged to surrounding environment. Particularly, there highly exists a possibility of containing heavy metals resulted from the automobile discharged gas, dust, and so on. In this regard, we sampled cleaning wastewater from each section of tunnel and analyzed COD, SS, T-N and T-P based on standard methods and also heavy metal content with IC(ion Chromatography) / ICP(Inductively Coupled Plasma). Additionally, we investigated the possibility of secondary contamination that can affect surroundings such as rivers and soil. The results indicate slightly large amount of COD, SS, T-N and T-P, and hazardous heavy metal content such as Cu, Pb. As a result of ionic analysis, we detected most cationic heavy metals and Cl of anionic components. As a study of the treatment of cleaning wastewater, it is thought that we must sufficiently investigate the case of advanced countries(e.g. Norway, Japan etc). In addition, it must be followed by the suitable selection and design of treatment process that accompanied with the analysis and prediction of wastewater generated periodically and seasonally