A stage apparatus includes a stationary support base-plate; a Y-direction moving member supported on the stationary support base-plate to move in a Y-direction; and an X-direction moving member supported on the Y-direction moving member to move in an X-direction orthogonal to the Y-direction. The Y-direction moving member includes a Y-direction rod portion which extends in the Y-direction and an X-direction rod portion connected to the Y-direction rod portion and extends in the X-direction. The stationary support base-plate includes a Y-direction guide device for guiding the Y-direction rod portion of the Y-direction moving member so as to slide in the Y-direction, and a Y-direction support device for supporting a free end of the X-direction rod portion so as to allow movement of the X-direction rod portion in the Y-direction. The X-direction moving member is supported by the Y-direction moving member so as to slide in the X-direction.