Acoustic emission (AE) characteristics of smoothed and notched specimens were investigated for a plain woven carbon fabric composite. The failure behavior of the smoothed specimen under tensile loading was estimated by the failure modes, AE parameters, and the load-elongation curve of the notched specimen. The results obtained are as follows:(1) The AE cumulative event count and the total AE energy of the smoothed specimen were larger than those of the notched specimen due to the difference in load level.(2) The AE amplitude distribution showed that the debonding of fiber/matrix and transverse/longitudinal fibers was the dominant failure mode before final fracture and generated much more AE than the fiber breakage. The AE activity of the smoothed specimen was larger than that of the notched specimen.(3) The load at the broken point of log-log plot for the total AE energy and stress intensity factor corresponded to the initiation of fiber/matrix debonding. It also agreed with the occurrence of AE.(4) The load-elongation curves of the smoothed and notched specimens could be divided into three parts. It was found that the initiation of the above debonding in the smoothed specimen can be estimated by the ratio of the load at the broken point to the maximum load of the notched specimen.