PURPOSE: To facilitate preparation of a pattern in high degree of integration and with high resolution by a method wherein a mask is made to comprise variable-transmittance elements of which the light transmittance can be varied by external signals and different pattern images are projected in a reduced manner by a plurality of times onto a semiconductor wafer or a reticle.

CONSTITUTION: A light emitted from a light source 1 is made to enter a condenser lens 3 directly or by reflecting it by a reflector 2. The light emitted from the condenser lens 3 irradiates a mask substrate 4. On the mask substrate 4, a large number of variable-transmittance elements 5 are formed and the transmittance of these variable-transmittance elements 5 is varied by signals supplied from signal lines 7 and 8. The light transmitted through the mask substrate 4 selectively is converged by a projecting lens 9 and imaged on a semiconductor wafer 12 placed on a stage. On the occasion, the relative relationship between the mask substrate 4 and the semiconductor wafer 12 is left fixed and a plurality of patterns are exposed. According to this constitution, interference of the light is prevented and a high resolution can be realized.