| 摘要 |
A spark plug (1) including a noble metal tip joined to a ground electrode and forming a spark discharge gap in cooperation with a center electrode. A surface of the noble metal tip which forms the gap has an area of 0.9 mm2 or greater. The noble metal tip (32) is joined to the ground electrode (27) via a fusion zone (35) formed by irradiating at least one surface among a distal end surface and side surfaces of the ground electrode with a laser beam or an electron beam. Further, as viewed on a projection plane orthogonal to a center axis of the noble metal tip and on which the noble metal tip and the fusion zone are projected along the center axis, an overlapping region between the noble metal tip (32) and the fusion zone accounts for 70% or more of a projected region of the noble metal tip.
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