A semiconductor device includes a source electrode and a drain electrode formed on an active region of the semiconductor layer, a gate electrode formed on the active region of the semiconductor layer, a first insulating film formed on the semiconductor layer and covering the gate electrode, the first insulating film having a step portion following a shape of the gate electrode, a first field plate formed on the insulating film and located between the gate electrode and the drain electrode and separated from the step portion, a second insulating film formed on the first insulating film to cover the step portion and the first field plate, and a shield electrode formed on the second insulating film, the shield electrode extending from a portion located above the first field plate and a portion located above the gate electrode.