A light filter and a spectrometer including the light filter are disclosed. The light filter includes a plurality of filter units having different resonance wavelengths, wherein each of the plurality of filter units includes a cavity layer configured to output light of constructive interference, a Bragg reflection layer provided on a first surface of the cavity layer, and a pattern reflection layer provided on a second surface of the cavity layer opposite to the first surface and configured to cause guided mode resonance of light incident on the pattern reflection layer, the pattern reflection layer including a plurality of reflection structures that are periodically arranged.