. Also, to achieve the above object, according to the present invention, there is provided a near-field optical microscope comprising: light illumination means for illuminating a sample surface of a sample with light; a probe having a top end provided at a position near the sample surface which is illuminated with the light; light detection means for detecting scattered light scattered by the probe; and scanning means for scanning the sample and the top end of the probe relatively to each other, wherein a top end diameter of the prove is equal to or smaller than xc0xc of a wavelength of the light illuminating the probe, and where a length of a range illuminated with the light from the 