Provided are a substrate supporting unit and a single type substrate polishing apparatus using the substrate supporting unit. During a polishing process, the bottom surface of a substrate is attached to the substrate supporting unit by vacuum suction, and during a post-cleaning process, the substrate is supported by the substrate supporting unit at a position spaced apart from the substrate supporting unit for cleaning the bottom surface of the substrate. Therefore, according to the substrate supporting unit and the substrate polishing apparatus using the substrate supporting unit, in a state where the substrate is supported by the single type substrate supporting unit, a process for polishing the top surface of the substrate and a post-process for cleaning the top and bottom surfaces of the substrate can be sequentially performed.