An improvement is achieved in the manufacturing yield of a semiconductor device including a plurality of field effect transistors having different characteristics over the same substrate. By combining anisotropic dry etching with isotropic wet etching or isotropic dry etching, three types of sidewalls having different sidewall lengths are formed. By reducing the number of anisotropic dry etching steps, in a third n-type MISFET region and a third p-type MISFET region where layout densities are high, it is possible to prevent a semiconductor substrate from being partially cut between n-type gate electrodes adjacent to each other, between the n-type gate electrode and a p-type gate electrode adjacent to each other, and the p-type gate electrodes adjacent to each other.