According to one embodiment, it is possible to provide a semiconductor device provided with an MIS transistor which has an effective work function being, as much as possible, suitable for low threshold operation. A CMIS device provided with an electrode having an optimal effective work function and enabling low threshold operation to achieve by producing an in-gap level by the addition of a high valence metal in an Hf (or Zr) oxide and changing a position of the in-gap level by nitrogen or fluorine or the like has been realized.