Improve a breakdown voltage and reliability of a semiconductor device. A plurality of semiconductor elements is formed in a cell region. A termination region surrounds the cell region in plan view. In a semiconductor substrate of the termination region, a p-type RESURF region is formed to reach a predetermined depth from an upper surface of the semiconductor substrate. The RESURF region is annularly formed in the termination region to surround the cell region in plan view. The RESURF region contains boron as an impurity.