Resonance Raman and infrared spectra of the organic superconductor K-(MDT-TTF),AUI, were measured to identify the vibrational modes which exhibit strong electron-molecular vibration (EMV) coupling. Excitation wavelength dependence of certain Raman modes was observed and is discussed in connection with the UV-visible absorption spectrum. Raman spectra measured at 77 K revealed a significant enhancement of a low-wavenumber mode attributed to the organic part, while the symmetric A d , -anion was found to be unaffected at low temperatures.