Patent ID: 8650933

Claim:
A gas sensor, comprising: a sensor element extending in an axial direction and having a detection portion for detecting gas to be detected at a front end thereof; a metal shell that surrounds a periphery of the sensor element in a radial direction while allowing the detection portion to protrude from a front end thereof; a cylindrical outer tube disposed at a rear side of the metal shell and having a front end fixed to the metal shell; and a seal member disposed in the outer tube, the seal member including: a lead wire insert hole into which a lead wire for extracting a detection signal of the detector is inserted, the lead wire insert hole extending in an axial direction thereof, and an atmosphere communication hole allowing atmospheric communication between an inside and an outside of the outer tube through a filter member having air ventilation and waterproofing properties, the atmosphere communication hole extending in an axial direction thereof, wherein the gas sensor further includes: a protection portion that protects the filter member by covering the atmosphere communication hole of the seal member from a rear end of the gas sensor in the axial direction, the protection portion having a protrusion which protrudes toward a rear side of the gas sensor, and has an opening smaller than an opening of the atmosphere communication hole, and wherein the protrusion is disposed entirely to the front of a rear end surface of the seal member.