(EN) ABSTRACT A method of fabricating a blank mask. The method includes forming a light-shielding film on a light-transmissive substrate to form an optical substrate; forming a photoresist layer on the light-shielding film; and removing droplets, generated in the forming of the photoresist layer, 5 from a side surface of the light-transmissive substrate, wherein the number of droplet-type adsorption, derived from the droplets, on the side surface of the light-transmissive substrate, is less than 3 per cm 2. (Fig. 1) 10 50