Abstract: A manufacturing method of a semiconductor device including a DMOS transistor, an NMOS transistor and a PMOS transistor arranged on a semiconductor substrate, the DMOS transistor including a first impurity region and a second impurity region formed to be adjacent to each other, the first impurity region being of the same conductivity type as a drain region and a source region of the DMOS transistor, forming to enclose the drain region, and the second impurity region being of a conductivity type opposite to the first impurity region, forming to enclose the source region, the manufacturing method of the semiconductor device comprising forming the first impurity region and one of the NMOS transistor and the PMOS transistor, and forming the second impurity region and the other of the NMOS transistor and the PMOS transistor.