A semiconductor device includes a first device isolation insulating film formed in a semiconductor substrate, a first well having a first conductivity type, defined by the first device isolation insulating film, and shallower than the first device isolation insulating film, a second device isolation insulating film formed in the first well, shallower than the first well, and defining a first part of the first well and a second part of the first well, a gate insulating film formed above the first part, a gate electrode formed above the gate insulating film, and an interconnection electrically connected to the second part of the first well and the gate electrode, wherein an electric resistance of the first well in a first region below the second device isolation insulating film is lower than an electric resistance of the first well in a second region other than the first region on the same depth level.