An apparatus and method for quantitatively sensing and analyzing a concentration of biomolecules using Raman peak shift are disclosed. The quantitative molecular sensing apparatus includes an illumination optical system including a light source configured to irradiate excitation light onto an object, a detection optical system including an optical detector configured to detect light scattered from the object, and a signal processor configured to analyze properties of the object based on signal output by the detection optical system and to calculate a concentration of target molecules in the object based on a Raman peak shift value over a predetermined time period.