An implantation step of a dopant ion for forming source and drain regions (S and D) is divided into one implantation of a dopant ion for forming a p/n junction with a well region (3), and one implantation of a dopant ion that does not influence a position of the p/n junction between the source and drain regions (S and D) and the well region with a shallow implantation depth and a large implantation amount. After conducting an activation heat treatment of the dopant, a surface of the source/drain region is made into cobalt silicide 12, so that the source/drain region (S and D) can have a low resistance, and a p/n junction leakage can be reduced.