Patent ID: 7379093

Claim:
A stage apparatus comprising: an X-direction movable member provided parallel to a reference plane and relatively movable to said reference plane only in a specific X-direction via an X-direction guide device; a Y-direction movable member supported by said X-direction movable member thereon to be movable only in a Y-direction orthogonal to said X-direction of said reference plane via a Y-direction guide device, wherein said X-direction movable member is provided in between a stationary support plate, which is parallel with said reference plane, and said Y-direction movable member; three ball retaining through-holes formed in said X-direction movable member at three vertices of an imaginary triangle; and three balls installed in respective said three ball retaining through-holes so as to contact said stationary support plate and said Y-direction movable member, wherein said three ball retaining through-holes allow each of said three balls to rotate in any rotational direction therein.