Spark plug having a ground electrode of specific alloy composition to which a noble metal tip is joined

A spark plug comprising:

• a cylindrical metal shell;
• a cylindrical insulator held by the metal shell;
• a center electrode held in the insulator;
• and
• a ground electrode that includes a ground electrode main body part having one end fixedly connected to the metal shell and the other end facing the center electrode, and a noble metal tip joined to the ground electrode main body part at a position facing a leading end of the center electrode, a spark discharge gap being formed between the leading end of the center electrode and the noble metal tip,
• wherein at least a portion of the ground electrode main body part, to which the noble metal tip is joined, is made of an alloy containing 12 to 45 mass % of Cr, 7 mass % or less of Fe, more than 0.5 mass % to 5 mass % or less of Al, more than 0.3 to 5 mass % or less of Si and Ni with 50 mass % or more of the rest of the contents, and
• wherein the joined portion and the noble metal tip are joined by laser welding or electron beam welding.