Abstract: In a semiconductor device having at least two conductive layers disposed close to each other on an element isolating insulation film formed on a first P-type region, a second P-type region is formed in a region of the first P-type region which is between the two conductive layers. The impurity concentration of the second P-type diffusion region is higher than the first P-type region. A region of the element isolating insulation film which is on the second P-type diffusion region is thin to form a thin insulation film. With the features, no inversion layer is formed in the region of the first P-type region where the second P-type diffusion region is formed. As a result, the inversion layers under the conductive layers will not be in contact with each other.