A semiconductor device includes: an active layer that is located in an SOI substrate, and in which an element included in a circuit is formed; a buried insulation layer that is located in the SOI substrate, and is in contact with the active layer; a deep trench isolation (DTI) region that is formed in the active layer to surround a whole formation region of the element in plan view, and extends from an upper surface to a lower surface of the active layer; and a first conductive film formed above the element. The DTI region has a first hole inside, and a film thickness of the first conductive film is greater than a thickness of the active layer.