A mask blank is equipped with a thin film that forms a mask pattern formed on a substrate and a chemically amplified type resist film that is formed above the thin film. In the mask blank, a protective film that prevents movement of a substance that inhibits a chemical amplification function of the resist film from a bottom portion of the resist film to inside the resist film is provided between the thin film and the resist film. The mask blank suppresses the error of the line width dimension of the transfer pattern formed on the substrate to the design dimension of the transfer pattern line width of the transfer mask (actual dimension error) and also suppress linearity up to 10 nm.