A plasmonic structure having an identifier pattern indicating a genuine product for preventing counterfeiting, falsification or reuse, includes a metal layer; a photoconversion pattern layer including a plurality of photoconverting nanoparticles disposed in a pattern on and in direct contact with the metal layer; a metal pattern layer including a plurality of metal particles disposed in a pattern on and in direct contact with the photoconversion pattern layer; and an adhesive film disposed on the metal pattern layer. An identifier pattern indicating a genuine product is easily identified even by visual inspection after irradiation with infrared light irradiation. The plasmonic structure is fundamentally impossible to re-assemble after deformation of the plasmonic structure caused by disassembly of a product or packaging container, thereby preventing counterfeiting, falsification or reuse.