The field-effect transistor is provided with at least: a substrate; a source electrode, a drain electrode and a gate electrode; a semiconductor layer that contacts the source electrode and the drain electrode; and a gate insulating layer that insulates the semiconductor layer from the gate electrode. The semiconductor layer contains carbon nanotubes, and the gate insulating layer contains a polymer in which inorganic particles are bonded. Provided are a field effect-transistor which has reduced leak current and enables uniform coating of a semiconductor solution, and a method for manufacturing the same.