Glow plug and method of manufacturing the same

A method of manufacturing a glow plug having a configuration in which a heater element generating heat upon supply of electric current thereto is positioned frontward or at a leading end of a tubular body, one of electrodes of the heater element is electrically connected to a metallic lead shaft member positioned inside the body and rearward with respect to the heater element, a rear end of the lead shaft member is inserted into an attachment hole opened at a leading end side of an external terminal, and the external terminal is fixed to the rear end of the lead shaft member,

• the method comprising a step of crimping the external terminal to fix the external terminal to the rear end of the lead shaft member after inserting the rear end of the lead shaft member into the attachment hole of the external terminal,
• an outer peripheral face of a crimp formation region of the external terminal before the crimping step being formed into a polygon in cross section, and
• characterized in that, in the crimping step,
• the outer peripheral face of the crimp formation region in cross section is shaped into a form close to a circle from the polygon shaped before the crimping step.