A photomask blank includes a chromium-based material film as a light-shielding film, wherein the chromium-based material film has an optical density per unit thickness at a wavelength of 193 nm of at least 0.050/nm, and the chromium-based material film has a tensile stress or compressive stress corresponding to an amount of warp of up to 50 nm.The present invention provides a photomask blank having a thin film of chromium-based material which is lowered in film stress while retaining a high optical density per unit film thickness. This enables high-accuracy patterning of a chromium-based material film.