Abstract: A method of bringing a surface of a wafer into coincidence with an image plane of a projection optical system on the basis of the detection of the deviation of the wafer surface from a reference plane of a deviation detecting sensor, includes the steps of: moving the wafer surface along an optical axis of the projection optical system, to a position close to the reference plane; detecting a deviation of the wafer surface from the reference plane; and moving the wafer surface on the basis of the detection, to be brought into coincidence with the image plane of the projection optical system.