To obtain a proximity effect correcting method used for manufacturing a mask obtained by combining both methods for correcting an electron beam proximity effect and a light proximity effect by calculating the light illuminance of an electronic beam required for correcting the electron beam proximity effect and the light proximity effect, executing electronic exposure operation by using a pattern corrected by the calculated result and manufacturing a photomask.

A computer aided design data collection forming the pattern on the mask is prepared. Then, a line 200 and a grid gate pattern 202 are included in the pattern. Next, the mask is divided into a first and a second patches according to the prepared pattern. Since the density of the pattern is related to the electron beam proximity effect and the contrast of light is related to the light proximity effect, the exposure of the electronic beam is adjusted by both of them so as to obtain the pattern whose proximity effects by the electronic beam and the light are corrected. By using the corrected pattern, the mask is formed by the proper exposure of the electron beam.