Abstract: There is provided an organic transistor having a bottom gate structure, composed of a substrate, a gate electrode, a gate insulating layer, source and drain electrodes and an organic semiconductor layer, wherein the gate insulating layer is formed so as to have a low surface energy in a portion thereof in proximity to the source and drain electrodes and a relatively high surface energy in a portion in proximity to the gate electrode, and consist of different compositions in a layer thickness direction, whereby an organic transistor has a short channel and high electric characteristics; as well as a method of manufacturing the organic semiconductor.