A method for manufacturing a water resistant optically anisotropic film capable of suppressing the generation of a defect such as a crack or separation is provided. The method for manufacturing the water resistant optically anisotropic of the present invention includes a water resistant treatment step of bringing an optically anisotropic film containing an organic dye having an anionic group into contact with a water resistant treatment liquid containing a multivalent cationic compound and a monovalent cationic compound, and the mass ratio of the multivalent cationic compound and the monovalent cationic compound contained in the water resistant treatment liquid, monovalent cationic compound/multivalent cationic compound, is 0.01 to 2.