In a halftone-type phase-shift mask blank having a phase shifter film 5, the phase shifter film 5 has a phase adjustment layer 4 for primarily controlling the phase of exposure light, and a transmissivity adjustment layer 3 which is formed between a transparent substrate 2 and the phase adjustment layer 4 and primarily controls the transmissivity of exposure light. The transmissivity adjustment layer 3 has a thickness of 90 angstroms or less.