A wafer stage installed in a process chamber for safely dechucking a wafer is provided. In one embodiment, the wafer stage comprises: a chuck support for supporting a chuck; a chuck mounted on the chuck support for receiving and attaching a wafer thereto; a support lift means for supporting the wafer; a driving means coupled to the support lift means for gradually raising the support lift means to contact the wafer in response to a variable quantity; a controller for receiving the variable quantity; and a regulating means coupled to the driving means and to the controller, the regulating means for controlling the variable quantity going to the driving means when a predetermined variable quantity is detected.