Provided is a molecular concentration measurement device including a laser oscillator oscillating and outputting first laser light with an oscillation frequency ω1 and second laser light with an oscillation frequency ω2 which are in a relationship of ωχ=ω1−ω2 (ω1>ω2) with regard to an oscillation frequency ωχ that is a molecule oscillation mode of molecules to be measured, a condensing lens condensing the first laser light and the second laser light into a blood vessel of an organism in which the molecules to be measured are included, a light sensing unit sensing stimulated Raman scattering light emitted by the molecules to be measured when the first laser light and the second laser light are radiated on the molecules to be measured, and then Stokes-shifted, and a concentration computation unit computing a concentration of the molecules to be measured from a spectral intensity of the sensed stimulated Raman scattering light.
