Patent ID: 7959482

Claim:
A method of manufacturing an ignition plug having an insulator with an axial hole, a center electrode provided in the axial hole, a substantially cylindrical metal shell and a plate-shaped ground electrode having a through hole formed in a center thereof, the method comprising: preparing an insulator having a cavity formed at a leading end portion thereof, said cavity formed by disposing a leading end of the center electrode in the axial hole of the insulator such that the leading end of the center electrode is recessed from a leading end of the insulator; assembling the insulator in an interior of the metal shell such that the leading end of the insulator is recessed from the leading end of the metal shell; removing at least part of a leading end portion of the metal shell which projects from a leading end face of the insulator; and disposing the ground electrode at the leading end portion of the metal shell and welding the ground electrode and the metal shell together.