An optical microcantilever for a scanning near field microscope comprises a support section, a cantilever-shaped optical waveguide, and a light blocking wall. The optical waveguide has a free end, a fixed end fixed to the support section and terminating in a light input/output end, and a tip formed at a side of the free end of the cantilever and having a microscopic aperture at an end thereof. The light blocking wall blocks the transmission of light scattered from a region of the light input/output end in the direction of the tip of the optical waveguide.