Patent ID: 8736154

Claim:
A spark plug comprising: a center electrode that extends in an axial direction; an insulation body that exposes a leading end of the center electrode and is formed at an outer periphery of the center electrode; a metal shell that is formed at an outer periphery of the insulation body, and a ground electrode that is connected to the metal shell, wherein the ground electrode has: a base material that is arranged so that a leading end portion thereof is opposite to an end surface of the center electrode; and a projecting shape section that is provided at the leading end portion of the base material and is formed in a projected shape at a portion close to the center electrode, wherein the base material and the projecting shape section are formed by a material of the same metal as a main component and are connected by resistance welding, and wherein the base material and the projecting shape section are formed to satisfy a relation R>S when a specific resistance of the base material is R (μΩcm) and a specific resistance of the projecting shape section is S (μΩcm).