A Levenson type phase shift mask has a light shielding portion and openings formed on a transparent substrate. The transparent substrate at the openings is partially dug in or a transparent film is partially disposed on the transparent substrate at the openings to form shifter openings and non-shifter openings. The shifter openings and the non-shifter openings repetitively exist in the mask. The shifter openings invert a phase of transmitted light. The Levenson type phase shift mask has a light shielding portions pattern interposed from both sides between the adjacent openings of the same kind. The light shielding portions pattern is subjected to bias correction which expands the light shielding portions pattern to both sides thereof in a predetermined amount with respect to a predetermined design line width set by a design of the mask.