To provide a light-emitting organic semiconductor element of a thin film transistor (TFT) type horizontal field type having three electrodes.

The light-emitting organic TFT element comprises a first and a second substrates arranged opposed to each other with a prescribed distance, a first electrode covered by an insulating membrane formed on the first substrate, a second electrode formed positioned with the first electrode in the plan view on the first substrate, a third electrode which is formed on the first or second electrode in the plan view and has a slit of prescribed width between the second electrode, and an organic semiconductor material layer clipped by the first and second substrates. The first electrode is formed in the region corresponding to at least the slit in the plan view, and in the state that a prescribed voltage is impressed between the second electrode and the third electrode, by controlling the voltage impressed on the first electrode, the luminance of emission in the vicinity of the prescribed region where the second electrode and the third electrode are adjoined can be controlled.