Glow plug

A glow plug 1 includes a sheathed heater 3 and a metallic shell 2. The sheathed heater 3 is configured such that a resistance wire coil 3b having a heating coil portion 30b and an insulating MgO powder 3d are placed in a sheath 3a and such that a bar electrode 3c is inserted into the sheath 3a. The heating coil portion 30b is formed of, for example, an Fe-Cr-A1 alloy, which exhibits, for example, excellent heat resistance. However, when the temperature of the heating coil portion 30b exceeds 1,000 DEG C, there arises a phenomenon that the heating coil portion 30b fails to exhibit expected durability. An object of the present invention is to provide the glow plug 1 that exhibits excellent durability at high temperature, particularly a high temperature in excess of 1,000 DEG C. The heating coil portion 30b is formed by a coil base material 31b and a coating layer 32b, which covers the surface of the coil base material 31b, and the coating layer 32b is formed of Pt, Pd, Rh, or an alloy of two or more of Pt, Pd, and Rh.