Abstract: Disclosed is a semiconductor device that comprises a first semiconductor layer of one conductivity type provided on a substrate; a second semiconductor layer of the one conductivity type provided on the first semiconductor layer and having a lower impurity concentration than the first semiconductor layer; an isolation region extending from one principal face of the second semiconductor layer to reach the substrate; a first region in an element region of the second semiconductor layer isolated by the isolation region and having an opposite conductivity type; a second region of the one conductivity type provided in the element region extending from the one principal face to reach the first semiconductor layer and having an impurity concentration higher than the second semiconductor layer; and an insulation region extending from the one principal face to the first semiconductor layer, kept away from the substrate, and provided between the first and the second regions.