A high-voltage vertical power component including a lightly-doped semiconductor substrate of a first conductivity type and, on the side of an upper surface, an upper semiconductor layer of the second conductivity type which does not extend all the way to the component periphery, wherein the component periphery includes, on the lower surface side, a ring-shaped diffused region of the second conductivity type extending across from one third to half of the component thickness; and on the upper surface side, an insulated ring-shaped groove crossing the substrate to penetrate into an upper portion of ring-shaped region.