The invention provides a nanostructure including nanowires having very small diameters and integrated at a high density, and capable of being applied to still further high-functional devices.The invention provides a structure including a substrate or substrate having an underlayer, and a structure formed on the substrate or substrate having an underlayer, wherein the structure includes a columnar first part (part) and a second part (part) formed to surround the first part, and the second part comprises two or more types of materials capable of forming eutectic crystals, one type of the materials is a semiconductor material, and the height of the first part from the substrate is greater than the height of the second part from the substrate.