A semiconductor device includes: a P-type semiconductor layer formed in a surface region of a semiconductor substrate; a first gate insulating film formed on the P-type semiconductor layer; a first gate electrode; and a first source region and a first drain region formed in the P-type semiconductor layer to interpose a region under the first gate electrode in a direction of gate length. The first gate electrode includes: a first silicide film formed on the first gate insulating film and containing nickel silicide having a first composition ratio of nickel to silicon as a main component; a conductive film formed on the first silicide film; and a second silicide film formed on the conductive film and containing nickel silicide having a second composition ratio of nickel to silicon as a main component. The second composition ratio is larger than the first composition ratio.