A method of providing a polymeric film with optical anisotropy by applying a polarized light to a polymeric film is disclosed. In the method, a photoisomerizable group or a photoisomerizable molecule has a T (thermal) type photochromic property capable of being isomerized by a thermal back reaction after the isomerization by light. The method includes two successive steps, that is, a step of applying a polarized light to the polymeric film and a step of shutting off a polarized light and leaving the film as it is, and controls the temperature of the polymeric film for enhancing the orientation of the photoisomerizable group or the photoisomerizable molecule induced by the thermal back reaction. An apparatus for practicing the method and an optical anisotropic medium having the polymeric film with high optical anisotropy obtained by the method are also provided.