A semiconductor device in which the retention characteristics of a rewritable memory cell packaged together with a field effect transistor including a metal gate electrode are improved and a method for manufacturing the semiconductor device. The semiconductor device includes a field effect transistor with a metal gate electrode and a rewritable memory cell. The manufacturing method includes the step of replacing a dummy gate electrode with the metal gate electrode. Before the step of replacing the dummy gate electrode with the metal gate electrode, the method includes the steps of making the height of the memory cell lower than the height of the dummy gate electrode and forming a protective film for covering the memory cell.