In a scanning exposure method, a mask stage that holds a mask is moved in a scanning direction by a first electromagnetic driver having a first portion coupled to the mask stage, and a second portion. A position of the mask stage is detected by a position detector that cooperates with a reflective portion of the mask stage that is positioned along the scanning direction. A counter weight having a bearing and at least one beam extending along the scanning direction moves in a direction opposite to a movement direction of the mask stage in response to a reaction force generated by movement of the mask stage by the first electromagnetic driver. The counter weight preferably is heavier than the mask stage, and a length of the at least one beam along the scanning direction preferably is longer than a length of the reflective portion along the scanning direction.