A semiconductor device includes a resistor element covered by a silicon oxide film. In the semiconductor device, with respective gate electrodes of MIS transistors and impurity doped layers, i.e., non-silicide regions exposed, thermal treatment for activating an impurity and silicidization are performed. Thus, auto-doping of an impurity is suppressed, so that variations in a resistance value of a resistor are suppressed. Also, the gate electrodes of the MIS transistors and the like are exposed when thermal treatment for activating an impurity, and therefore breakdown of respective gate insulation films of the MIS transistors hardly occurs.