A semiconductor device includes a semiconductor substrate, an nMISFET formed on the substrate, the nMISFET including a first dielectric formed on the substrate and a first metal gate electrode formed on the first dielectric and formed of one metal element selected from Ti, Zr, Hf, Ta, Sc, Y, a lanthanoide and actinide series and of one selected from boride, silicide and germanide compounds of the one metal element, and a pMISFET formed on the substrate, the pMISFET including a second dielectric formed on the substrate and a second metal gate electrode formed on the second dielectric and made of the same material as that of the first metal gate electrode, at least a portion of the second dielectric facing the second metal gate electrode being made of an insulating material different from that of at least a portion of the first dielectric facing the first metal gate electrode.