SPARK PLUG

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An object of the present invention is to provide a spark plug including a noble metal tip exhibiting intended durability; specifically, a noble metal tip exhibiting excellent erosion resistance, separation resistance, and breakage resistance. The spark plug of the present invention is characterized in that (1) the noble metal tip contains Mp (Mp is Pt or Pt and Pd, and the amount of Pd is 20 mass% or less with respect to the mass of the noble metal tip), Cu, and M (M is at least one element selected from the element group consisting of Rh, Ir, Ru, Re, and W) in a total amount of 95 mass% or more, and the proportions by mass of Mp, Cu, and M fall within specific ranges, or (2) the proportions by mass of Mp, Cu, and M (Mp, Cu, M) fall within specific ranges, and welding area S (mm 2 ), tip protrusion height H (mm), covering length L (mm), and tip-welded portion distance h (mm) satisfy the following relations : (a) H ‰¤ 0.13S + 1.18, (b) S ‰¤ 5, and (c) 0.1 ‰¤ h or 0.03 ‰¤ L.