The evaluation of the wear conditions is an important subject in energy saving and resource conservation. Therefore, though the friction coefficient, etc. are measured, it is difficult to evaluate the wear conditions with Non-destructive inspection. In this study, the system which evaluated the wear conditions by the wavelet transform (WT) results of the detected AE signals during the wear testing was examined. As the result, the following things became clear. (1) From the WT results, the possibility of grasping the frequency ranges which rise from the wear phenomenon was able to be shown. (2) The possibility of deciding the sign of seizure was able to be shown. (3) The validity of this system could be explained by the collation with the experiment results.