Gas sensor

A gas sensor comprising:

• a sensor element that has an atmospheric-air introduction path into which atmospheric air is introduced, wherein:
• the sensor element includes
• a solid electrolyte body that has ion conductivity,
• an insulating body that is laminated onto the solid electrolyte body,
• an exhaust electrode that is provided in the solid electrolyte body and exposed to an exhaust gas, and
• an atmosphere electrode that is provided in a position that opposes the exhaust electrode in the solid electrolyte body, is used so as to be paired with the exhaust electrode, and is exposed to atmospheric air;
• the atmospheric-air introduction path is formed so as to house the atmosphere electrode in a section of the insulating body that opposes the solid electrolyte body;
• the atmospheric-air introduction path is provided with a trap layer for capturing toxic substances in the sensor element, the trap layer being formed to include a porous body of a metal oxide that has insulating properties;
• in the trap layer, macropores and inter-particle gaps are formed, the macropores being formed because of unevenness in a distribution of particles of the metal oxide, the inter-particle gaps being smaller than the macropores, and being formed between the particles of the metal oxide;
• and
• an average pore diameter of the macropores is equal to or greater than 0.4μ, and is less than the average film thickness of the trap layer.