This invention relates to a method of fabricating a three-dimensional copper nanostructure, including manufacturing a specimen configured to include a SiO2 mask; performing multi-directional slanted plasma etching to form a three-dimensional etching structure layer on the specimen; performing plating so that a multi-directional slanted plasma etched portion of the specimen is filled with a metal; removing an over-plated portion and the SiO2 mask from the metal layer; and removing a portion of a surface of the specimen other than the metal which is the three-dimensional etching structure layer. In this invention, a uniform copper nanostructure array can be obtained by subjecting a large-area specimen disposed in a Faraday cage to multi-directional slanted plasma etching using high-density plasma, forming a copper film on the etched portion of the specimen, and removing an over-plated copper film and the SiO2 mask, and the diameter of the copper nanostructure can be arbitrarily adjusted, thus attaining high applicability.