A spark plug includes an electrode wherein a plurality of fusion regions are formed by melting to each other a circular noble metal tip having a diameter of not less than 2 mm and a base material disposed around an outer periphery of the noble metal tip. In a particular tip cross section, a total length of the portions passing the fusion region on the circumference of a circle A concentric to an outline of the tip and having a diameter of 90% of the length of the tip is not less than 30% of the length of the circumference of the concentric circle A, and a total length of the portions on which a circumference of a concentric circle B, having the same diameter as that of the outline passes, is not less than 30% of the length of the circumference of the concentric circle B.