In a near-field scanning microscope using an aperture probe, the upper limit of the aperture formation is at most several ten nm in practice. In a near-field scanning microscope using a scatter probe, the resolution ability is limited to at most several ten nm because of the external illuminating light serving as background noise. Moreover, measurement reproducibility is seriously lowered by a damage or abrasion of a probe. Optical data and unevenness data of the surface of a sample can be measured at a nm-order resolution ability and a high reproducibility while damaging neither the probe nor the sample by fabricating a plasmon-enhanced near-field probe having a nm-order optical resolution ability by combining a nm-order cylindrical structure with nm-order microparticles and repeatedly moving the probe toward the sample and away therefrom at a low contact force at individual measurement points on the sample.