A stage apparatus includes a stationary support plate; a Y-direction moving member including a Y-direction rod portion and an X-direction rod portion connected thereto parallel with the stationary support plate, the Y-direction moving member being supported by the stationary support plate so as to relatively move in the Y-direction; an X-direction moving member supported by the X-direction rod portion so as to relatively move in the X-direction. One of the X-direction moving member and the stationary support plate is provided with a projection, and the other of the X-direction moving member and the stationary support plate is provided with a rotation restriction support portion supporting the projection to move in a plane parallel with the stationary support plate relative to the other of the X-direction moving member and the stationary support plate and which prevents rotation of the X-direction moving member about the X-direction rod portion.