To provide a method for forming the mask pattern of a mask in which a pattern correction calculating time can be shortened, and an influence due to a light proximity effect can be precisely suppressed by suppressing the deterioration of the through-put of drawing.

In a mask pattern forming method at the time of forming a mask for an optical lithography by electron beam drawing, an exposure process by an electron beam is constituted of a first exposure process for operating exposure with constant exposure to the whole area of a pattern area 10, and a second exposure process for operating exposure with prescribed exposure to prescribed areas 100a-100d including edges 10a-10d. Thus, the correction of a light proximity effect in optical lithography can be precisely operated, and the deterioration of the through-put of pattern drawing can be suppressed by using the mask in which the mask pattern is formed.