PROBLEM TO BE SOLVED: To provide an optical measurement device suitable for measuring the distribution of lipids in a blood vessel.SOLUTION: Illumination light outputted from an optical branch part 32 is made incident on a proximal end 11a of an optical fiber 11 and emitted from a distal end 11b to irradiate an object 3 with the illumination light, back reflection light generated in the object 3 following the irradiation is made incident on the distal end of the optical fiber 11 and emitted from the proximal end to guide the back reflection light to an optical detector 33 and guide reference light outputted from the optical branch part 32 to the optical detector 33, interference light by the back reflection light and the reference light are detected by the optical detector 33, a spectrum of the back reflection light is analyzed by an analyzer 36 to generate tomographic structure information of the object and distribution information of material inside the object, and the tomographic structure information and the distribution information of the material are analyzed in combination to calculate a tomographic image in which the distribution of the material inside the object is displayed.
