A thin film field effect transistor includes at least: a substrate; and a gate electrode, a gate insulating layer, an active layer, a source electrode and a drain electrode, and a protective layer provided on the substrate in this order from the substrate side. The active layer is a layer containing an amorphous oxide containing at least one metal selected from the group consisting of In, Sn, Zn and Cd. The thin film field effect transistor further includes, between the active layer and at least one of the source electrode or the drain electrode, an electric resistance layer containing an oxide or nitride containing at least one metal selected from the group consisting of Ga, Al, Mg, Ca and Si.