To provide a semiconductor device in which a gate parasitic capacitance component Cgs between a gate electrode and a source electrode can be reduced.

A semiconductor device comprises: an operation layer 12 formed on a semiconductor substrate 11; a drain electrode 13 and source electrode 14 formed so as to be spaced apart from each other on a surface of the operation layer 12; a gate electrode 15 formed between the drain electrode 13 and the source electrode 14 on the surface of the operation layer 12; a surface protection film 19 formed between the drain electrode 13 and the source electrode 14 so as to cover the gate electrode 15 on the surface of the operation layer 12; a source field plate electrode 20 formed at a position overhanging at least an end portion of the gate electrode 15 on a drain side on a surface of the surface protection film 19; and a plurality of wiring lines 21 formed on the surface protection film 19, the plurality of wiring lines being electrically connected to the source field plate electrode 20 and the source electrode 14 and being smaller in width than the electrodes 20 and 14.