To provide a spark plug that can reduce power loss and prevent erosion of a tip end part of a central electrode, even in a configuration such that a discharge current and an electromagnetic wave are emitted from a terminal fitting part of the spark plug, a...

To provide an ignition plug having low power loss even though iron is a main component of a center electrode thereof, to which a high frequency power such as a microwave is electrically supplied. A low impedance layer 6 composed of a material having magnet...

An ignition plug (1) includes a ceramic insulator (2) having an axial bore (4), a center electrode (5) inserted into the axial bore (4) in such a manner that a forward end surface thereof is located rearward of the forward end of the insulator (2), a metal...