The semiconductor device includes: a semiconductor substrate; a conductor layer formed over the semiconductor substrate and having an upper surface and a lower surface; a conductive pillar formed on the upper surface of the conductor layer and having an upper surface, a lower surface, and a sidewall; a protection film covering the upper surface of the conductor layer and having an opening which exposes the upper surface and the sidewall of the conductive pillar; and a protection film covering the sidewall of the conductive pillar. Then, in plan view, the opening of the protection film is wider than the upper surface of the conductive pillar and exposes an entire region of an upper surface of the conductive pillar.