A semiconductor device includes: a SOI substrate; a semiconductor element having first and second impurity layers disposed in an active layer of the SOI substrate, the second impurity layer surrounding the first impurity layer; and multiple first and second conductive type regions disposed in a part of the active layer adjacent to an embedded insulation film of the SOI substrate. The first and second conductive type regions are alternately arranged. The first and second conductive type regions have a layout, which corresponds to the semiconductor element.