A semiconductor device is provided which can be manufactured even by using an inexpensive FZ wafer in a wafer process and still has a sharp inclination of a high impurity concentration in a high impurity concentration layer at the outermost portion of the reverse side and at the boundary between the high impurity concentration and a low impurity concentration drift layer, thus achieving both low cost and a high performance. A method for manufacturing a semiconductor device is also provided which can form a high impurity concentration buffer layer and a high impurity concentration layer at the outermost portion of the reverse side without any significant trouble, even after the formation of an active region and an electrode thereof at the right side, to thereby achieve both low cost and high performance.