To provide a screw for grounding capable of increasing a contact area by increasing adhesion between a soldering part and a head seat surface, and capable of reducing a variation of ground resistance.

In the screw for grounding, a screw shaft 12 is screwed into a substrate supporting part supporting an electric substrate through a lower hole formed at the electric substrate, and the head seat surface is brought into contact with the soldering part deposited at the periphery of the lower hole, and the soldering part and the substrate supporting part are made to be electrically conductive, and an annular protrusion having a center axis of the screw shaft as the center is provided on the head seat surface. The annular protrusion is preferably an endlessly continuous protrusion, but may be a non-continuous protrusion.

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