Provided is a spectrometer. The spectrometer includes: a light source part configured to emit light of a plurality of wavelengths onto an object; a detector configured to detect an optical signal of each of the plurality of wavelengths as reflected from the object; a controller configured to set an amplification gain for each of the plurality of wavelengths according to photoreaction properties of the object; and an amplifier configured to amplify an output signal of the detector by using the set amplification gain.