A semiconductor device of an embodiment includes a silicon carbide layer having a first and a second plane, a trench, a gate electrode in the trench, an n-type first silicon carbide region, a p-type second silicon carbide region and a p-type third silicon carbide region provided between the first silicon carbide region and the first plane and interposing the trench therebetween, a p-type sixth silicon carbide region between the first silicon carbide region and the second silicon carbide region, a p-type seventh silicon carbide region between the first silicon carbide region and the third silicon carbide region, an eighth silicon carbide region between the first silicon carbide region and the sixth silicon carbide region, and a ninth silicon carbide region between the first silicon carbide region and the seventh silicon carbide region. The eighth silicon carbide region has a plurality of first regions extending toward the ninth silicon carbide region.