PURPOSE: To simultaneously satisfy the large exposure field and the high resolution by diffracting the light passed through the pattern of a mask via a projection optical system, and reproducing a mask pattern on a sample from the diffracted light to be exposed.

CONSTITUTION: A diffraction grating A is inserted between a mask 1 and a projection optical system 2, and a diffraction grating B is inserted between the system 2 and a wafer 4. The mask is obliquely emitted from a different direction. In this case, both the gratings A and B are assumed to be phase gratings and that the illuminated lights R, L from the two directions are coherent to each other. A zero order light R0 reaches a point A0 on the grating A, where the light diffracted in + primary direction is passed through the left end of a pupil 3, and arrived at a point B0 on the grating B. Thereafter, it is diffracted by the grating B in + primary and - primary directions, and arrived at Q and P on image surfaces. The + primary diffracted light R1 arrives at the point A1 on the grating A, where the light diffracted in the + primary direction is passed through the right end of the pupil, and arrived at the point B1 on the grating B.