Patent ID: 7420139

Claim:
A glow plug comprising: a rod-shaped ceramic heater including a ceramic heater body extending axially, a heating portion embedded in a front end portion of said ceramic heater body and being capable of generating heat upon energization, and a pair of lead portions each having one end connected to said heating portion, and the other end exposed to an outer circumferential surface of a rear end portion of said ceramic heater body; a rod-shaped center pole extending axially so as to electrically connect to the outside; and a cylindrical member including a front end portion bonded to an outer circumferential surface of a rear end side of said ceramic heater, and a rear end portion bonded to an outer circumferential surface of a front end side of said center pole, said cylindrical member being made by a metal material for electrically connecting one of said pair of lead portions and said center pole to each other, wherein said cylindrical member has a Vickers hardness of not lower than 200 HV at 25° C.