PURPOSE: To maintain the accuracy of correcting a deflecting distortion for a long period by obtaining a first deflecting distortion value of the entire drawing region by reflecting electrons from a first mark of a heavy metal, and correcting the first deflecting distortion value by a second mark on a substrate to be exposed to decide the correcting value of the distortion at exposing time in an electron beam exposure.

CONSTITUTION: When second deflecting distortion values 8aW8d are completely measured, the ratios of the second deflecting distortion values 8aW8d to the first deflecting distortion values 5aW5d of specific positions 7aW7d are respectively calculated, the average value is used as a proportional coefficient C, and applied to a control register of a deflecting system D. Then, in case of drawing a picture, the coefficient C is multipiled by the first value 4 of the drawing position, with the obtained value as a correcting value 6a it is corrected to draw the picture. When a desired pattern 2 is drawn in this manner, the drawn pattern 3b after correction coincides substantially with the pattern 2. The measurements of the values 8aW8d are desired to be executed at every substrate to be exposed. Thus, the correction for the distortion can be always follow the variation in a charge-up drift.