The object is to fabricate a novel organic semiconductor element which can effectively utilize the main-chain conduction of a conjugated high molecular compound having semiconductor-like properties. Provided is an electronic element which contains, as components, a pair of electrodes which is formed on a substrate, a mesoporous film in which tubular mesopores, which are orientation controlled in one direction, are formed, the mesoporous film being formed between the electrodes so as to be in contact with the electrodes, a conjugated high molecular compound held in the tubular mesopores, and a third electrode which is electrically insulated from the conjugated high molecular compound and is in contact with the mesoporous film.