A MOS transistor of the present invention includes a semiconductor substrate included with a first conduction type-impurity; a gate insulating layer formed on the semiconductor substrate; gate electrodes formed on the gate insulating layer; an oxide layer formed by the surface oxidation of the gate electrodes; a first spacer formed on the side wall of the gate electrodes; a second spacer formed on the inclined side wall; a first impurity layer of low concentration formed in a first depth by a second conduction type-impurity implanted in the vicinity of surface of the semiconductor substrate to be self-aligned at the edge of the gate electrode; a second impurity layer of middle concentration formed in a deeper second depth than the first depth by the second conduction type-impurity implanted in the vicinity of surface of the semiconductor substrate; a third impurity layer having higer impurity concentration than that of the semiconducor, the third impurity formed in a third depth for surrounding the second impurity layer of middle concentration by a first conduction type-impurity implanted in the vicinity of surface of the semiconductor substrate to be self-aligned at the edge of the first spacer; and a fourth impurity layer of high concentration formed in a fourth depth deeper than the third depth by the second conduction type-impurity implanted in the vicinity of the surface of the seminconductor substrate to be aligned at the edge of the second spacer.