A projection exposure apparatus (1) comprises an incident light optical system for causing the light emitted from a light source 1 to enter an object of exposure (4) in diagonal direction, a detection apparatus (3) for causing an interference between the light reflected from the object of exposure (4) and a reference light and detecting the resultant interference fringe, a processing circuit for determining the inclination and height of the surface of the object of exposure (4) from the optical information on the interference fringe, and a stage (7) for supporting the object of exposure (4). The object of exposure (4) is subjected to projection exposure by driving the stage (7) according to the calculated inclination and height of the object of exposure (4).