There are provided a method of manufacturing a semiconductor device which achieves a reduction in implantation masks, and such a semiconductor device. By implanting boron into NMOS regions using a resist mask and another resist mask as the implantation masks, p-type impurity regions serving as the halo regions of access transistors and drive transistors are formed. By further implanting phosphorus or arsenic into a PMOS region using another resist mask as the implantation mask, n-type impurity regions serving as the halo regions of load transistors are formed.