An ignition plug includes a metallic shell containing iron as a main component, carbon in an amount of 0.20 wt. % to 0.30 wt. %, manganese in an amount of 0.30 wt. % to 0.45 wt. %, and sulfur in an amount of 0.005 wt. % to 0.009 wt. %. The ratio of the manganese content (wt. %) to the sulfur content (wt. %); i.e., Mn/S is 40 to 65.