PURPOSE: To produce a metal thin film of long sheet form having a hairline of desired angle, by developing after providing a slit at desired angle, with respect to the hairline of cylindrical metal thin film produced to have a hairline in the longitudinal direction.

CONSTITUTION: Metal thin films of long sheet form having hairline in the longitudinal direction are glued together so that the hairlines may run in the longitudinal direction of cylinder, and a cylindrical metal thin film having hairlines 6 in the longitudinal direction is produced. Next, this cylindrical metal thin film is slit at a desired angle, and developed into a metal thin film of long sheet form. As a result of this, the hairlines 6 form a desired angle with respect to the longitudinal direction of the metal thin film of long sheet form. This metal thin film of long sheet form is, for example, by using a thin aluminum film, applied as a reflection layer in a reflection type polarizing film.