A semiconductor device including a first semiconductor layer including a first region and a second region adjacent to the first region; a first insulator layer provided above the first semiconductor layer; an intermediate semiconductor layer, having an n-type conduction, provided above the first region of the first semiconductor layer and above the first insulator layer; a second insulator layer provided above the intermediate semiconductor layer; a second semiconductor layer provided above the first region of the first semiconductor layer and above the second insulator layer; a sensor formed in the second region of the first semiconductor layer; a contact electrode connected to the intermediate semiconductor layer; and a circuit element formed in the second semiconductor layer.