To improve characteristics and/or the reliability of a static induction transistor in which an electrically conductive high polymer is used.

The static induction transistor 30 comprises a first electrode 1, a second electrode 2, a semiconductor layer 3 which lies therein and serves as a current path between the first electrode 1 and the second electrode 2, and a third electrode 4 buried in the semiconductor layer 3. A current between the first electrode 1 and the second electrode 2 is controlled by controlling a voltage applied to the third electrode 4. The semiconductor layer 3 contains a first hyper-branch high polymer. Moreover, the semiconductor layer 3 has a self-organized structure based on non-covalent-bond interaction via the first hyper-branch high polymer.