A system of optical beating spectroscopy has been newly developed for hyper‐resolution Brillouin scattering. Frequency resolution as high as 1 kHz was obtained, far beyond the limit of the classical Fabry–Perot interferometer which is commonly used in ordinary experiments. This system is useful over the frequency range from 104to 109Hz at present. Experiments for Rayleigh and/or Brillouin spectra were performed in water, toulene, and carbon disulfide to demonstrate the performance of this system.