Providing an optical measurement probe having an optical system disposed within a small diameter to be sufficiently separated from the measuring light and the irradiation light can. The region α the region away 2/2 or more distance d inside from the outer periphery of which can be installed inside area ω the receiving end 2a of the optical fiber system 2 and a second exit end 1a of the optical fiber system of the first, second the region β region of 1 + d 2 is less than the diameter d of the center axis center axis 1X the exit end of the optical fiber system 1, the exit of the optical fiber system of the first about the optical axis 3X of the condenser lens system 3 When was the area γ an area of 1 + d 2 less than the diameter d to the central axis (coordinate -P1) axis at the position of symmetry and (coordinates P1) the central axis of the end, out of the area α, region and area β γ δ in the region not including the center axis 2X of the receiving end of the optical fiber system of the second is arranged. The distance d 3 axis with the position of the symmetrical and (coordinates -P1), and the center axis of the light receiving end of the optical fiber system and the second, (d 1 + d 2) / 2
