An object of the present invention is to provide a polarizer, a method of producing a polarizer, a laminate, and an image display device which enable achievement of both the degree of alignment and heat resistance. The polarizer of the present invention is a polarizer formed of a polarizer-forming composition which contains a liquid crystal compound and a dichroic material, in which the liquid crystal compound has a smectic liquid crystallinity, and a phase transition temperature of the polarizer-forming composition from a smectic phase to an isotropic phase or a nematic phase is 120° C. or higher.