To obtain an optical element for generating near-field light which can accurately detect positions of a plurality of minute structures formed on a metallic thin film provided to a condensing surface, and a method of adjusting an optical spot position of the optical element. The metallic thin film is formed on the condensing surface of the optical element that condenses incident light so as to generate near-field light smaller than an condensing spot B near a condensing point, and a plurality of openings (minute structure) for generating the near-field light are formed into a matrix matter on the metallic thin film, and position detecting structures are formed on positions that partitions the openings is formed. Scanning in X and Y directions is carried out by a light beam, and its reflected light is detected so that the positions of the openings are detected.