Switching element

In a switching element using, for the active layer, a carbon nanotube (CNT) dispersed film which can be manufactured at low temperatures, the interaction between the CNT and the surface of the gate insulating film is insufficient. For this reason, a problem of such a switching element is that the amount of CNT fixed in the channel region is insufficient, resulting in insufficient uniformity. In the switching element of the exemplary embodiment, a gate insulating film is formed of a nonconjugated polymer material containing, in the main chain, an aromatic group and a substituted or unsubstituted alkylene or alkyleneoxy group having 2 or more carbon atoms as repeating units. As a result, the interaction between the CNT and the surface of the gate insulating film is enhanced while maintaining the flexibility of the gate insulating film, and the amount of CNT fixed in the channel region can be increased. Thereby, a switching element having good and stable transistor characteristics can be obtained by a low-temperature, simple, and inexpensive process.