Provided is a highly reliable semiconductor device. This semiconductor device comprises: a semiconductor substrate (10) having a first region (NP1) and a second region (NP2); a first insulator layer (2b); a first gate electrode (3b) having a first semiconductor layer (31b) that contains an impurity, a first conductor layer (32b) that contains titanium, a second conductor layer (33b) that contains nitrogen and either titanium or tungsten, and a third conductor layer (34b) that contains tungsten; a second insulator layer (4b) that is provided on the third conductor layer and that contains oxygen and silicon; a third insulator layer (5b) that is provided on the second insulator layer and that contains nitrogen and silicon; a first contact (CS) provided on the first region; a second contact (CS) provided on the second region; and a third contact (C0) that is provided on the third conductor layer of the first gate electrode and that penetrates through the second insulator layer and the third insulator layer.