A glow plug having a main body bracket, a heater, a center shaft, an insulator, an O-ring that is provided between the front end surface of the insulator and the main body bracket, and a pin terminal that is fitted to the rear end portion of the center shaft and used for supplying electricity from the outside. The pin terminal includes a small-diameter portion, a flange, and a large-diameter portion where an engagement portion and a fitting recess are formed. The large-diameter portion includes a crimp formation region, which is formed so as to have the even outer diameter and be capable of being crimped, in a range from the front end thereof to the front end of the engagement portion. A part of the crimping target portion forms a crimping portion that fixes the rear end portion of the center shaft by crimping.