A metallic probe having a nano-scaled tip strongly enhances the optical field in the local vicinity of the tip apex. Using this effect, which is analogous to the surface enhanced Raman scattering, we can excite Raman scattering in a nanometric region, and consequently realize nano-identification, nano-analysis and nano-imaging of molecules and crystals. In this article, we introduce the mechanism and recent results of the tip-enhanced near-field Raman scattering spectroscopy. In particular, unique spectral shapes observed in the tip-enhanced Raman scattering spectra are discussed via a quantum chemical calculation. We also demonstrate that tip-enhanced spectroscopy has been applied to nonlinear Raman scattering and has achieved molecular nano-imaging with a high resolution and a high sensitivity.