Semiconductor device

The semiconductor device comprises: a semiconductor substrate (N+ substrate 110 ) containing a first conductivity type impurity implanted therein; a second conductivity type impurity-implanted layer (P+ implanted layer 114 ) at relatively high concentration, formed on the semiconductor substrate (N+ substrate 110 ); a second conductivity type impurity epitaxial layer (P- epitaxial layer 111 ) at relatively low concentration, formed on the second conductivity type impurity-implanted layer (P+ implanted layer 114 ); and a field effect transistor 100 (N-channel type lateral MOSFET 100 ) composed of a pair of impurity diffusion regions (N+ source diffusion layer 115 and N- drain layer 116 ) provided in the second conductivity type impurity epitaxial layer (P- epitaxial layer 111 ) and a gate electrode 117 provided over a region sandwiched with the pair of impurity diffusion regions (N+ source diffusion layer 115 and N- drain layer 116 ).