By using a blanking aperture array BAA, the density of the bit map data in the portions where adjacent areas are linked is decreased toward the outside. On the lower surface of the holder of the BAA chip, a ball grid array wired to blanking electrodes is formed, to be pressed in contact against pads on a wiring base board. The registered bit map data for an isosceles right triangle are read out from address A=A0+�RA.multidot.i! (A0 and i are integers, � ! is an operator for integerizing), masked, and then shifted by bits to be deformed. From registered bit map data for proximity effect correction, the area which corresponds to the size of the object of correction and the required degree of proximity affect correction is extracted, and logic operation with the bit map data of the object of correction is performed to achieve proximity affect correction. Before figures data are expanded into bit map, a checksum is determined in units of bit map data corresponding to the range of one session of scanning over which continuous exposure is possible. A sine wave voltage is provided to an electrostatic deflector and during a one-shot exposure period, an electron beam is caused to scan for an integer number of times on a block of a mask and the positional misalignment of the electron beam at the lower aperture stop is corrected.