A light comb generating device according to a disclosed embodiment includes a light source for generating light in a reference wavelength band and outputting the generated light, and an optical comb generator for generating a light comb having a reference comb interval from the output light, wherein the light source changes a wavelength of the output light as much as a reference frequency interval for every reference time interval, the light comb is generated within a wavelength range of the reference frequency interval, and the reference wavelength band may be at least about 3 μm and no greater than about 30 μm.