A substrate supporting apparatus for supporting a substrate or wafer in a non-contact state by Bernoulli theorem is disclosed. The substrate supporting apparatus 1 comprises a housing 2, a rotatable chuck 3 which is disposed in the housing 2, which is provided at its central portion with a hollow 12 and which supports a substrate 6, and a cylindrical nozzle member 4 which is disposed in the housing 2, which has a nozzle hole 7 and which can vertically move in the hollow 12. A nozzle hole 7 is formed in a central portion of the nozzle member 4. Gas is discharged from a gas source 8 through the nozzle hole 7, thereby holding the substrate 6 by an upper surface of the chuck 3 in a non-contact state. When the substrate 6 is to be detached, the nozzle member 4 is moved upward while discharging gas from the nozzle hole 7, thereby floating the substrate 6.