A Raman spectroscopic apparatus analyzes a substance under analysis and includes a light source that emits light of a first wavelength, an optical device that adsorbs the substance under analysis and is irradiated with the light of the first wavelength, and an optical detector that receives light radiated from the optical device. The optical device includes a first structural member that generates charge transfer resonance in response to the light of the first wavelength and a second structural member that is less than or equal to 5 nm from the first structural member and generates surface plasmon resonance in response to the light of the first wavelength. The first structural member is made of a metal or a semiconductor, and the second structural member is made of a metal different from the material of the first structural member.