Provided is a mask blank that is improved in adhesion of a thin film for forming a transfer pattern to a resist, thus capable of suppressing the occurrence of collapse, chipping, or the like of a formed resist pattern. The mask blank has, on a transparent substrate 1, a thin film 2 which is for forming a transfer pattern and is made of a material containing a metal. The thin film 2 has a surface modified layer in the form of an oxide film containing a hydrocarbon. The surface modified layer of the thin film 2 can be formed by, for example, causing a highly concentrated ozone gas and an unsaturated hydrocarbon gas to act on the thin film.