A semiconductor device includes a first first-conductivity-type semiconductor layer, a second first-conductivity-type semiconductor layer provided on a major surface of the first first-conductivity-type semiconductor layer; a third second-conductivity-type semiconductor layer being adjacent to the second first-conductivity-type semiconductor layer, provided on the major surface of the first first-conductivity-type semiconductor layer, and forming a periodic array structure in combination with the second first-conductivity-type semiconductor layer in a horizontal direction generally parallel to the major surface of the first first-conductivity-type semiconductor layer, and a sixth semiconductor layer located outside and adjacent to the periodic array structure of the second first-conductivity-type semiconductor layer and the third second-conductivity-type semiconductor layer, provided on the major surface of the first first-conductivity-type semiconductor layer, and having a lower impurity concentration than the periodic array structure. The amount of impurity in the outermost semiconductor layer of the first conductivity type or the second conductivity type adjacent to the sixth semiconductor layer in the periodic array structure is generally half the amount of impurity in the second first-conductivity-type semiconductor layer or the third second-conductivity-type semiconductor layer inside the outermost semiconductor layer.