A polishing pad cleaner of a chemical mechanical polishing apparatus throughly and efficiently cleans the polishing pad of the apparatus. The respective input data are switchedoutput to N output terminals through a switch. Second, a bias set is determined. A correction coefficient data extraction unit extracts correction coefficient data in accordance with an elapsed time of the zero-cross point signal generated by the zero-cross detection unit from a rotation number correction coefficient data table, and outputs the data to a corrected rotation number creation unit.