A gas floated workpiece supporting apparatus includes a gas upward ejector ejecting gas upward, and a gas downward ejector located at an upper side from the gas upward ejector and ejecting gas downward. The gas downward ejector is installed at a position where the gas downward ejector ejects the gas downward from above a plate-shaped workpiece to apply pressure to the plate-shaped workpiece that is floated and supported by the gas ejected from the gas upward ejector, whereby a uniform floating amount supports the plate-shaped workpiece with high flatness at a time of floating and supporting the plate-shaped workpiece.