PURPOSE: To obtain a mask for exposing and its production method possible to reduce the dependency of exposing condition to kind or dimension of a pattern, possible to improve the limit of resolution of a transfer device and possible to truly transfer the pattern with constant light quantity.

CONSTITUTION: The mask such as a stepper used for a exposing device consists of a transparent glass substrate 1 and a light shielding film of a metal oxide film 30 formed on the surface of the substrate. The light shielding film has a prescribed light transmission and a feature possible to shift the phase of light for exposing. The light shielding film is made by depositing a metallic film on the transparent substrate and thermally oxidizing it to form an oxidized film 30. The width of the distribution of light intensity becomes sharp because the phase of transmitted light is shifted.