Fine structure body, process for producing the same, and Raman spectroscopic method and apparatus

X=A−BC×A fine structure body comprises: (i) a base body, and (ii) a plurality of metal nanorods, which have been distributed and located on a surface of the base body, a proportion X being equal to at least 15%, the proportion X being calculated with the formula:/100[%] wherein A represents the sum total of the projected areas of all of the metal nanorods, B represents the sum total of the projected areas of certain metal nanorods, each of which is located as an isolated metal nanorod at a spacing larger than 10 nm from the closest metal nanorod, and C represents the entire projected area of the fine structure body, including regions free from the metal nanorods.