The probe (1) is provided with: a light-receiving optical fiber (10) having an entrance face (12) on the tip that is orthogonal to a first optical axis (11) a light-emitting optical fiber (20) having an exit face (22) on the tip that is orthogonal to a second optical axis (21) and a lens (30) with a positive refractive power that projects light exiting from the exit face (22) onto the measurement site of a living tissue and focuses light radiated from the measurement site of the living tissue onto the entrance face (12). The lens (30) has a convex surface (34) that faces the entrance face (12) and exit face (22), a flat surface (36) formed on the side opposite the convex surface (34), and a third optical axis (31). The distance (L1) from the center (35) of the convex surface (34) to the first optical axis (11) of the light-receiving optical fiber (10) is shorter than the distance (L2) from said center (35) to the second optical axis (21) of the light-emitting optical fiber (20).
