Ignition plug and ignition apparatus

摘要

[Objective] To provide a technique for lowering power loss involved in supply of high-frequency electric power to an ignition plug. [Means for Solution] An ignition plug includes a tubular insulator having an axial bore extending therethrough in the direction of an axis; a center electrode disposed in a forward end portion of the axial bore; a metal terminal disposed rearward of the center electrode in the axial bore, electrically connected to the center electrode, and supplied with high-frequency electric power from an external source; a metallic shell disposed in such a manner as to circumferentially surround the insulator; and a ground electrode electrically connected to the metallic shell and adapted to generate plasma in cooperation with the center electrode through supply of high-frequency electric power to the metal terminal. At least a portion of the inner surface of the axial bore is coated with metal coating; the center electrode is in electrical contact with the metal coating; and the metal terminal is in electrical contact with the metal coating at a position located rearward of the center electrode.