This study is associated with pad conditioning using a high-pressure jet. The high-pressure jet is expected as a non- destructive conditioning method to achieve excellent pad cleaning and the long pad life. However, it is necessary to indicate the extent of the effect quantitatively in order to demonstrate the effect of conditioning. In this study, the authors proposed a method to evaluate pad cleanliness quantitatively by counting pores and debris on the pad surface. Cleanliness is one of the parameters representing the surface properties of the pad. Furthermore, the authors investigated the effect of cleaning by the high-pressure jet in accordance with the proposed method. As a result, it was possible to distinguish the difference of the cleaning effect quantitatively according to the difference of cleaning condition parameters. The results of this study can be applied to the evaluation of pad conditioning effect, and are useful for such as optimization of pad conditioning.