According to one embodiment, a semiconductor device includes a silicon carbide member. The silicon carbide member includes an operating region including at least one of a diode or a transistor, and a first element region including at least one element selected from the group consisting of Ar, V, Al and B. The first element region includes a first region and a second region. A first direction from the first region toward the second region is along a [1-100] direction of the silicon carbide member. The operating region is between the first region and the second region in the first direction. The first element region does not include a region overlapping the operating region in a second direction along a [11-20] direction of the silicon carbide member. Or the first element region includes a third region overlapping the operating region in the second direction.