A field-effect transistor is provided, which includes an organic thin film and which can realize a low threshold voltage while a stable, high field-effect mobility is ensured at the same time. In a field-effect transistor provided with a gate electrode, a source electrode, a drain electrode, a semiconductor film, a gate insulating film, and a substrate, the gate insulating film is formed from a plurality of insulating layers. Here, a first insulating layer in contact with the semiconductor film is formed from poly-p-xylylene formed into a film by a CVD method. A second insulating layer is formed from, for example, cyanoethylpullulan, and the dielectric constant is specified to be higher than that of the first insulating layer.