A semiconductor device includes a drain layer, a drift layer, a base region, a source region, trenches, base contact region, gate regions, and field plate electrodes. The drain layer extends in a first and a second direction. The drift layer is on the drain layer. The base region is on the drift layer. The source region is on the base region. The trenches are in an array and each trench reaches the drift layer from the source region. The base contact region is along the second direction in a region in which the trenches do not contiguously exist along the second direction and electrically connects the source region to the base region. Each gate regions is along an inner wall of the trenches. Each field plate electrodes is in an inside of the gate regions and is longer than the gate regions in the third direction.