A spark plug having a center electrode and a ground electrode that form a gap therebetween. At least one of the center electrode and the ground electrode includes a portion formed of a nickel alloy containing nickel as a major component and 20% by mass or more of chromium. In the portion, formed of the nickel alloy, of the electrode, the content of silicon is 0.1% by mass or more, the total content of one or more particular elements selected from the group consisting of rare earth elements is 0.01% by mass or more, and the area percentage of voids in the total area of a cross-section parallel to a longitudinal direction is 1% or less.