A positioning device for positioning an object includes a movable member movable in X and Y directions, a top plate, disposed above the movable member, for mounting the object, at least four driving units, disposed between the top plate and the movable member, for driving the top plate with respect to the movable member in a Z direction, a position measuring unit for measuring positions of the top plate in the X and Y directions, and a controller for selecting three of the driving units based on an output from the position measuring unit. Another positioning device includes a movable member, a top plate, a driving unit for driving the top plate with respect to the movable member, a measuring unit for measuring a position of the top plate at an elastic mode node, and a controller for controlling the driving unit based on output from the measuring unit.