The controller includes a deflection signal generator for generating a deflection signal for causing the electron beam to deflect and perform overwriting so that a beam spot of the electron beam follows the translation of the substrate over a period during which the substrate is rotated over a predetermined number of overwriting cycles; and a data output unit for outputting the drawing data, wherein, the deflection signal generator generates a deflection adjustment signal for irradiating the electron beam at a starting position for drawing a concentric circle to be subsequently overwritten after a predetermined deflection adjustment period has elapsed since overwriting of concentric circles based on the drawing data has completed.