The grinding operation is an important machining process for machining of final surface. However, grinding process has inevitable troubles such as loading and glazing for grinding wheel. It is, therefore, an essential research theme to determine the wheel life and the dressing time for efficient grinding. In this study, AE signals (AEavg) generated in the grinding operation were measured and the dressing time was determined from the analysis of the AEavg value. To verify the propriety of the obtained result, the AE signals measured on the grinding and the dressing operation were compared with the grinding force signals and the dressing force which were measured at same time. From the obtained result, it was confirmed that the determination of the wheel life and the dressing tilde by the AE measurement technique proposed in this study can be practically used.