There is provided a near-field-light (NFL) generating optical system in which the point where near-field (NF) light is generated can be provided sufficiently close to the end surface of a magnetic pole that generates write field. The optical system comprises: a waveguide through which a light for exciting surface plasmon propagates; and a NF-optical device configured to be coupled with the light in a surface plasmon mode. The NF-optical device comprises: an opposed-to-waveguide surface opposed to the waveguide with a predetermined distance; and a propagation edge provided on the side opposite to the opposed-to-waveguide surface, extending to the NFL-generating end surface of the device, and configured to propagate thereon the surface plasmon excited by the light. In this optical system, the point, where NF-light is generated, of the NFL-generating end surface can be located on the side opposite to the waveguide.