an object is to provide acid - resistant , highly reliable phase shift masks , and phase shift mask blanks , wherewith high - precision patterning is possible . a halftone phase shift mask blank comprising a transparent substrate 10 , a halftone material film 11 laminated on that transparent substrate , and a metal film 12 laminated on that halftone material film , wherein the metal film is formed by a plurality of metal films having different etching rates , and the etching rate for the metal film positioned on the transparent substrate side is set so that it is faster , either in stages or continuously , than the etching rate of the metal film positioned on the surface side .