PURPOSE: To prevent the degradation of an optical-intensity profile at a defocus in a FLEX exposure method.

CONSTITUTION: An exposure operation under a (high-coherency) condition under which a coherency factor δ is small shows a tendency in which a drop in optical intensity at a defocus becomes remarkable while optical intensity in the center of a pattern is large, and an exposure operation under a (low-coherency) condition under which the coherency factor δ is large shows a tendency which is opposite to it. Then, three or more exposure points including a focal point are set along the optical axis in the same exposure point, the coherency factor δis made lower in the exposure point in the center or near the center than that in the exposure points other than it, and merits under both conditions are combined. The value of the coherency factor δ is lowered in such a way that a stepper in which a variable diaphragm has been inserted into a fly-eye face is used, that the opening of the variable diaphragm is made narrow and that the numerical aperture NA1 of an illumination optical system is reduced.