Provided is a sensor for biological detection. The sensor for biological detection includes: a sensing unit including a light generator, an optical coupler, and an optical detector, the optical coupler dividing light incident from the light generator to project divided lights into a bio chip and a reference unit, respectively, and coupling the lights reflected from the respective bio chip and reference unit as one output light, and the optical detector detecting the output light, and the bio chip is independently separated from the sensing unit to be disposed on paths of lights divided by the optical coupler. The sensing unit has a composition of the Michelson interferometer.