To provide a stage device which enables reduction in size and weight.

When a stage WST whereon an object is mounted is driven in an X-axis direction by a first driving mechanism, the reaction force of a driving force acts on a part of the first driving mechanism. However, in this process, a first counter weight 79 with prescribed weight is moved by a control device with respect to an X-axis direction in the opposite direction of the movement direction of a stage via first axial linear motors 80A, 80B. In the process, the control device drives a first counter weight at a velocity in accordance with the weight of the stage WST and the first counter weight 79, and thereby the reaction force can be canceled by the reaction force of the driving force of the first counter weight. Accordingly, the weight of the first counter weight can be reduced compared to the case that the reaction force of the stage is canceled by the free motion of the first counter weight following the principle of the conservation of momentum.