A semiconductor device includes: a first semiconductor layer; a second semiconductor layer; a two-dimensional carrier gas layer; a source electrode; a drain electrode; a gate electrode; and an auxiliary electrode located above the two-dimensional carrier gas layer between the gate electrode and the drain electrode. Channel resistance of the two-dimensional carrier gas layer between the gate electrode and the auxiliary electrode is set higher than channel resistance of the two-dimensional carrier gas layer between the gate electrode and the source electrode.
