The effect of washing on electromagnetic wave shielding effectiveness(SE) has been studied. The shielding effectiveness of electromagnetic wave shielding fabrics decreased as the washing time increases. From the observation of SEM, AFM, and EDX, it was found that decrease in shielding effectiveness was caused by corrosion and removal of the plated metals from the surface of electromagnetic wave shielding fabrics during washing. Reduction of shielding effectiveness via washing is strongly dependent upon the washing temperature and the shielding effectiveness of electromagnetic wave shielding fabric after 30 min. of washing above 6$0^{circ}C$ is very low.