A birefringent pattern builder, having an optically anisotropic layer containing a polymer having unreacted reactive groups,wherein the optically anisotropic layer is produced by a method containing the steps [1] and [2] in this order: [1] coating and drying a solution containing a liquid crystalline compound having at least two kinds of reactive groups; and [2] reacting one kind of the at least two kinds of reactive groups by applying heat or irradiating ionizing radiation.