The present invention provides an optical measurement device of biological tissue having a probe attachable to a moving part of a living body with a high curvature in biophotometry. A member having a high flexibility and a high friction coefficient is disposed on a surface for contact with the living body. In addition, a device for light irradiation and a device for collection of light are fixed with an elastic material for uniform pressure application. The resulting double structure or double layer has solved a problem.