There is disclosed a polishing cleaning mechanism configured to be in contact with a rear surface of a substrate which is held in a substrate holding unit for holding the rear surface of the substrate and perform a polishing process and a cleaning process on the rear surface of the substrate, including a cleaning member configured to clean the rear surface of the substrate, a polishing member configured to polish the rear surface of the substrate, and a support member configured to support the polishing member and the cleaning member to face the rear surface of the substrate held in the substrate holding unit, wherein a surface of the polishing member facing the substrate and a surface of the cleaning member facing the substrate differ in relative height from each other.