Patent ID: 8215153

Claim:
A gas sensor comprising: a detection element that extends in an axial direction, the detection element having a detection portion that detects a concentration of a specific gas in a measured atmosphere, the detection portion being positioned in a leading end side of the detection element; a metal shell that surrounds the detection element so as to expose the detection portion to the measured atmosphere; an outer tube that is fixed to the metal shell so as to cover a rear end side of the detection element; and a seal member that is contained inside the outer tube, the seal member having a lead wire insertion hole into which a lead wire is inserted for electrically connecting the detection element and an external device and a through hole that penetrates in the axial direction, the gas sensor further comprising: a tubular holding member made of a resin having a lower coefficient of thermal expansion than the seal member, the holding member being held inside the through hole, the holding member having a ventilation hole that introduces a gas into an inside of the outer tube; a filter that covers the ventilation hole, the filter being joined to the holding member, the filter blocking water from passing therethrough, and the filter having air permeability; and a mesh that covers the filter from a rear end side, the mesh being made of metal or a resin having air permeability, wherein the mesh has a higher air permeability than the filter.