SPARK PLUG AND INTERNAL COMBUSTION ENGINE

The objective of the present invention is to improve the heat conductance of the center electrode of the spark plug in which its center electrode protrudes to the combustion chamber from the defining surface of the chamber. The ignition plug of the present invention comprises a center electrode to where high voltage for spark discharge is applied; an insulator having a penetration hole to where the center electrode is fit; and an earth electrode that forms a discharge gap between the center electrode at where the spark discharge is generated. The center electrode protrudes from a defining surface of an internal combustion engine to a combustion chamber when the ignition plug is attached to the engine. The entirety of a main body of the center electrodes that is fixed by fitting into a penetration hole of the insulator is made of high heat conductance material having heat-conductivity of 250 W / mK or more.