GLOW PLUG AND METHOD FOR MANUFACTURING SAME

An improvement in fuel economy, a reduction in manufacturing costs, an improvement in quick temperature rising characteristic and a conservation of electric power are realized, while preventing reduction in holding force for holding a heater member by a holding portion. A glow plug 1 includes a cylindrical housing 2 having an axial hole 4 which extends in a direction of an axis CL1 and provided with, on an outer circumferential surface thereof, a screw portion 5 for being screwed into a mounting hole of an internal combustion engine, and a heater member 3 which is inserted into the axial hole 4 in a state where at least a front end portion thereof projects from a front end of the housing 2. The housing 2 includes a pressure contact portion 7 brought into pressure contact with a seat surface of the internal combustion engine when the screw portion 5 is screwed into the mounting hole of the internal combustion engine, and a cylindrical front-end-side body portion 9 provided between the pressure contact portion 7 and the screw portion 5. The front-end-side body portion 9 includes a holding portion 20 which holds the heater member 3 directly or indirectly at an inner circumference thereof, and the holding portion 20 has a smallest outer diameter in the front-end-side body portion 9.