There is disclosed an optical measurement device which is based on optical interference and it uses a light beam which is radiated to and transmitted through or reflected by a sample, especially a light scattering medium to optically measure the sample. The amount of signal lights effective for optical heterodyne detection is increased, while speckle noises are averaged out. On an observation plane of a concerned point arranged are plural detector elements. From signals obtained by the respective detector elements, an optical signal of the concerned point is obtained.