An optical measurement probe, which is capable of adequately separating an irradiation beam and a measuring beam, and which has an optical system arranged in a fine diameter, is provided. When a region, which is separated by a distance d2/2 or greater to the inside from the outer circumference of an internal ω region that enables a light-emitting end (1a) of a first optical fiber system (1) and the light-receiving end (2a) of a second optical fiber system (2) to be set, is regarded as α region, a region having a diameter of less than d1 + d2, which is regarded as the central axis of the central axis (1X) of the light-emitting side of the first optical fiber system, is regarded as β region, and a region having a diameter of less than d1 + d2, which is regarded as the central axis of an axis (coordinate -P1), which is in a position symmetrical to the central axis (coordinate P1) of the light-emitting end of the first optical fiber system, as the center of the optical axis (3X) of a condenser lens system, is regarded as γ region, the central axis (2X) of the light-receiving end of the second optical fiber system is positioned in δ regions, which do not contain the region β and the region γ, in the α region. Furthermore, a distance d3 between the axis (coordinate -P1), which is in the abovementioned symmetrical position, and the central axis of the light-receiving end of the second optical fiber system satisfies the relationship, (d1 + d2)/2 < d3 < D - (d1 + d2)/2.Linvention porte sur une sonde de mesure optique, qui est apte à séparer de façon adéquate un faisceau de rayonnement et un faisceau de mesure, et qui comporte un système optique agencé sous un diamètre fin. Quand une région, qui est séparée dune distance d2/2 ou plus par rapport à lintérieur à partir de la périphérie externe dune région interne ω qui permet à une extrémité démission de lumière (1a) dun premier système de fibre optique (1) et à une extrémité de réception de lumière (2a) dun second système de f
