Patent ID: 7291961

Claim:
A spark plug comprising: a center electrode having a tip end portion; an insulator which holds said center electrode therein in a state where the tip end portion of said center electrode protrudes therefrom; a metal shell which holds said insulator therein; a ground electrode which is fixed to said metal shell, said ground electrode having an inner side face; a discharge portion in which a noble metal tip is bonded to said inner side face of said ground electrode by laser welding, a discharge gap being formed between said discharge portion and said tip end portion of said center electrode; and a molten bond, in which said noble metal tip and said ground electrode are melted together, wherein an unmelted portion of said noble metal tip protrudes from said molten bond, and wherein said molten bond has a shape in which a middle portion on a side of said metal shell is inward recessed as viewed from a tip end face of said noble metal tip, and a minimum distance between an outer peripheral edge of said molten bond in said recessed portion and an outer peripheral face of said noble metal tip is 0.25 mm or more.