A technology of restraining junction leakage in a semiconductor device is to be provided. There is provided a semiconductor device provided with a semiconductor substrate, a gate electrode 9 formed on the semiconductor substrate, and a source/drain region formed beside the gate electrode, wherein the source/drain region 4 comprises a first impurity diffusion region including a first P-type impurity and located in the proximity of a surface of the semiconductor substrate, and a second P-type impurity diffusion region located below the first impurity diffusion region and including a second P-type impurity having a smaller diffusion coefficient in the semiconductor substrate than the first P-type impurity.