A semiconductor device includes first and second MOSFETs corresponding to at least first power source voltage and second power source voltage lower than the first power source voltage, and non-silicide regions formed in drain portions of the first and second MOSFETs and having no silicide formed therein. The first MOSFET includes first diffusion layers formed in source/drain portions, a second diffusion layer formed below a gate portion and formed shallower than the first diffusion layer and a third diffusion layer formed with the same depth as the second diffusion layer in the non-silicide region, and the second MOSFET includes fourth diffusion layers formed in source/drain portions, a fifth diffusion layer formed below a gate portion and formed shallower than the fourth diffusion layer and a sixth diffusion layer formed shallower than the fourth diffusion layer and deeper than the fifth diffusion layer in the non-silicide region.