The carbon fiber reinforced plastics(CFRP) have been widely used in aircraft and spacecraft structures as well as sports goods because it has high specific strength, high specific stiffness and low coefficient of thermal expansion. Machining of CFRP poses problems not frequently seen for metals due to the nonhomogeneity, anisotropy, and abrasive characteristics of CFRP. Delamination is a common problem faced while drilling holes in CFRP using conventional drilling. Therefore, AE characteristics related to drilling damage process of unidirectional and [0/90/]s crossply laminate composite was studied. Also drilling damage like the delamination was observed by video camera in real time monitoring technique. From the results, we basically found the relationships between the delamination from drilling and AE characteristics for CFRP composites.