There is provided a field effect transistor having an organic semiconductor layer, including: an organic semiconductor layer containing at least porphyrin; and a layer composed of at least a polysiloxane compound, the layer being laminated on the organic semiconductor layer so as to be in intimate contact with the organic semiconductor layer. As a result, there can be provided a field effect transistor which enables an organic semiconductor layer having high crystallinity and high orientation to be formed and which exhibits a high mobility.