A semiconductor device including: a well layer that is formed on a semiconductor substrate; a first impurity diffusion layer that is formed on the well layer; a floating gate that is formed on the well layer in one region isolated from the first impurity diffusion layer, with a gate insulating film therebetween, and that is drawn over the first impurity diffusion layer and over the well layer in other region isolated from the first impurity diffusion layer, respectively; a source or drain layer that is formed on the well layer in such a manner that the source or drain layer sandwiches the floating gate disposed on the gate insulation film with another source or drain layer and in isolation from the first impurity diffusion layer; and a second impurity diffusion layer that is formed on the well layer adjacently to the other region, the well layer being of a first conductivity type while the source or drain layer, the first impurity diffusion layer and the second impurity diffusion layer being each of a second conductivity type.