A semiconductor device includes a p-type SiC layer, a gate electrode, and a gate insulating layer between the SiC layer and the gate electrode. The gate insulating layer includes first and second layers and first and second regions. The second layer is between the first layer and the gate electrode and has a higher oxygen density than the first layer. The first region is across the first layer and the second layer, and includes at least one first element selected from the group consisting of N (nitrogen), P (phosphorus), As (arsenic), Sb (antimony), and Bi (bismuth) and the first region having a first concentration peak of the at least one first element. The second region is provided in the first layer, includes a second element from Ta (tantalum), Nb (niobium), and V (vanadium) and, the second region having a second concentration peak of the at least one second element.