A near field optical head of a compact structure for reproducing information recorded at a very high density, at a good S/N ratio. A recording medium (3) which emits a light on application of an electric field is formed on an electrode (2), and a near field optical head (101) in which an inverted conical hole is formed in a slider (31) with its top part as a minute aperture (6) is brought close to the recording medium (3). A minute electrode (5) is formed on a lateral side (32) of the inverted conical hole, and an electric field (9) is applied only to a minute area of the recording medium (3) so as to emit a light, thus enabling detection of only the light emission in the minute area at the aperture (6).