A process for preparing a metal nanostructure having metal masses with zero valence aligned on a substrate surface wherein the size and shape of the metal masses are controlled is described. The process can include preparing a micro phase separation membrane of an amphiphilic block copolymer on a substrate and then exposing the membrane to a solution containing metal ions; drying the membrane to form a micro phase separation membrane with the metal ions localized in hydrophilic segments of the membrane; and irradiating vacuum ultraviolet light on the membrane to reduce the metal ions and to remove organic materials.