light measuring light through the reticle 1 and furthermore the projection optical system 3 and evaluates it the evaluating unit 5 is arranged beside the projection optical system 3 and has an illumination unit 6 a focal point changing unit 7 a photo receiving unit 8 such as an image sensor and the like the illumination unit 6 emits measuring light toward a reflecting surface second optical element 11 formed on a reference member provided to a reticle stage original stage 10 along a predetermined optical path to illuminate a focus mark formed on the reference member 13 through the reference member 11 the focal point changing unit 7 changes the focal point of the evaluating unit 5 by a relay lens or the like the reticle stage 10 can move in a three dimensional direction while holding the reticle 1 and is provided with the reference member 11 having a reflecting surface the wafer stage 12 can move in the three directional direction while holding the wafer 2 and is provided with the reference member 13 having the focus mark a reticle stage height detector 14 measures the position i e the height of the reticle stage 10 in direction of the optical axis z direction of the projection optical system 3 a wafer stage detector.