A stage apparatus includes a stationary support plate; an X-direction moving member supported on the stationary support plate by an X-direction guide device; and a Y-direction moving member supported on the X-direction moving member by a Y-direction guide device. The X-direction guide device has an X-direction elongated hole extending in the X-direction and formed in one of the X-direction moving member and the stationary support plate, and an X-direction engagement projection provided on the other of the X-direction moving member and the stationary support plate and is engaged in the X-direction elongated hole. The Y-direction guide device has a Y-direction elongated hole extending in the Y-direction and formed in one of the X-direction and Y-direction moving members, and a Y-direction engagement projection which is provided on the other of the X-direction and Y-direction moving members and is engaged in the Y-direction elongated hole.