Decrease in optical near-field intensity is prevented when an light
propagating medium made of a high refractive index material, such as a
waveguide or a lens, is combined with a scatterer for producing optical
near-field. Near the optical near-field generating element, a second
light propagating medium is disposed in contact with a first light
propagating medium of a high refractive index material, such as a
waveguide or a lens. The refractive index of the second light propagating
medium is made smaller than the refractive index of the first light
propagating medium.