PURPOSE: To improve the resolution exceeding the diffraction limit by emitting the light from a light source to a mask, diffracting the pattern of the mask, diffracting the diffracted light through a projection optical system, and reproducing the pattern on a sample to be exposed.

CONSTITUTION: A mask 1 is inserted between a projection optical system 2 and diffraction gratings A, B, and a diffraction grating C is inserted between the system 2 and a wafer 4. In this case, the gratings A, B, C are simultaneously phase gratings. The light R perpendicularly incident to the mask 1 is diffracted to zero order diffracted light R0, + primary diffraction light R1 and - primary diffracted light R1' on the mask surface. The light R0 arrives at a point A0 on the grating A, and the light diffracted in the - primary direction is diffracted to + primary direction at the point B0 on the grating B. Thereafter, it is diffracted at the point C0 on the grating C via the left end of the pupil 3 in ± primary direction, and arrived at two points Q, P on the image surfaces.