Patent ID: 7847472

Claim:
A spark plug comprising: a center electrode; an insulator which holds said center electrode therein in a state where a 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 having a width that is smaller as it advances toward a tip end side, in a portion of the inner side face positioned between a pair of tapered faces; a discharge portion in which a noble metal tip is bonded to said inner side face of said ground electrode by laser welding so as to attain a diameter of 0.8 mm or less and a height of 0.5 mm or more, 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, formed so as to extend from said inner side face to each of said tapered faces, said molten bond having a curved shape which protrudes outward in a convex shape at a corner formed between said inner side face and each of said tapered faces.