A semiconductor device includes an active layer, a source electrode, a drain electrode, a gate electrode, a first insulating layer, a gate metal layer, a via, a first source metal layer, a drain metal layer, and a second source metal layer. The source electrode, the drain electrode, and the gate electrode are present on the active layer. The first insulating layer is present on the source electrode, the drain electrode, and the gate electrode. The gate metal layer, the first source metal layer, the second source metal layer, and the drain metal layer are present on the first insulating layer. The gate metal layer includes a narrow portion and a wider portion. The via is present between the metal gate layer and the gate electrode. The second source metal layer is present between the gate metal layer and the drain metal layer.