1. A device for detecting nerves containing unmyelinated nerves, the device comprising: excitation light irradiation means for irradiating a sample with excitation light; means for detecting Raman scattering light from the sample; a spectroscopic portion for dispersing the received Raman scattering light into a spectrum component of each wavelength/wave number; intensity ratio calculation means for calculating an intensity ratio of a specific wavelength/specific wave number of the Raman scattering light or analyzing means for extracting a feature of the intensity ratio and subjecting the feature to multivariate analysis and/or statistical analysis; and means for specifically displaying (i) nerves including myelinated nerves and unmyelinated nerves, separate from other tissue, and (ii) unmyelinated nerves, separate from myelinated nerves and other tissue, using the intensity ratio as an index.