A photomask blank comprises a transparent substrate, a light-shielding film deposited on the substrate and comprising a metal or metal compound susceptible to fluorine dry etching, and an etching mask film deposited on the light-shielding film and comprising another metal or metal compound resistant to fluorine dry etching. When the light-shielding film is dry etched to form a pattern, pattern size variation arising from pattern density dependency is reduced, so that a photomask is produced at a high accuracy.