An object of the invention is to provide a higher-durability spark plug
provided with a center electrode and a side electrode. At least one of
the center electrode and the side electrode includes a precious metal
member facing a spark discharge gap between the electrodes. A sweating
phenomenon of the precious metal member can be suppressed while spark
abrasion, oxidation abrasion and abnormal abrasion of the precious metal
member are suppressed. The precious metal member contains Ir as a main
component, and smaller amounts of Rh, Ru, and Ni.