A dressing apparatus is used to resurface a polishing surface of a polish cloth used to polish semiconductor wafers. A dressing brush which spins on its own axis is also coupled to a drive shaft of a main drive of the dressing apparatus through a planetary gear mechanism so that the brush will rotate or orbit about the drive shaft. Therefore, the dressing brush traces a complex path and its dressing action is spread over a wide surface area of the polishing cloth to produce thorough resurfacing of the polishing surface. The service life of the cloth is significantly increased and contributes to improving the overall efficiency of preparing high quality polished semiconductor wafers. For economy, the dressing apparatus can be mounted easily on a conventional polishing apparatus having a dressing facility.