A mask blank includes a glass substrate including a first main surface and a second main surface, an absorbing film formed above the first main surface, and a conductive film formed on the second main surface. A reflective film is provided between the absorbing film and the glass substrate. In a surface of the conductive film on an opposite side to the glass substrate, when a surface shape of a square central area having a length of 142 mm and a width of 142 mm excluding a four-sided frame-shaped peripheral area thereof is expressed by the specific formula, flatness of a component obtained by summing all aklPk(x)Pl(y) with the sum of k and l being 3 or more and 25 or less is 20 nm or less.