A flat stage apparatus is provided to reduce manufacturing cost by displacing a flat plate with an arbitrary thrust force in a direction orthogonal to a plane of the plat plate. A flat stage apparatus includes a flat plate(1), a support member(10), a moving tool, and an air bearing(11). A workpiece is mounted on the flat plate. The support member supports the flat plate in at least three positions. The moving tool moves the flat plate in parallel. The air bearing is disposed at the support member to face the flat plate. The support member displaces the flat plate in a perpendicular direction to the flat plate and maintains the displaced state. The moving tool includes a moving portion and a platen. The moving portion includes a polarity for generating a moving magnetic field. The platen is installed to face the air bearing.