A semiconductor device is provided with a drain electrode 22, a semiconductor base plate 32, an electric current regulation layer 42 covering a part of a surface of the semiconductor base plate 32 and leaving a non-covered surface 55 at the surface of the semiconductor base plate 32, a semiconductor layer 50 covering a surface of the electric current regulation layer 42, and a source electrode 62 formed at a surface of the semiconductor layer 50. A drift region 56, a channel forming region 54, and a source region 52 are formed within the semiconductor layer 50. The drain electrode 22 is connected to a first terminal of a power source, and the source electrode 62 is connected to a second terminal of the power source. With this semiconductor layer 50, it is possible to increase withstand voltage or reduce the occurrence of current leakage.