Patent ID: 8021616

Claim:
A gas sensor comprising: a gas detection element extending from a leading end thereof to a base end thereof in an axial direction, the leading end of the gas detection element being exposed to a gas to be measured; a metal shell extending from a leading end thereof to a base end thereof in the axial direction and holding the gas detection element such that the gas detection element protrudes from the leading end of the metal shell; and a metal cylinder extending from a leading end thereof to a base end thereof in the axial direction, a leading end portion of the metal cylinder surrounding a base end portion of the metal shell and being fixed to the metal shell via a circumferential welded portion, wherein the metal shell comprises: Fe in an amount equal to or more than 50.0 mass %; C in an amount of 0.02 mass % to 0.15 mass %; Cr in an amount of 11.5 mass % to 18.0 mass %; and Nb in an amount equal to or more than twice the amount of C in mass %.