Gas sensor

A gas sensor comprising:

• a detection element section that has an elongated shape in a longitudinal direction, and includes a solid electrolyte with oxygen-ion conductivity, a detection electrode which is located on a surface of the solid electrolyte and is exposed to gas to be detected, and a reference electrode located on the surface of the solid electrolyte;
• a heater that includes a heating section that generates heat by energization, the heater being configured to heat the solid electrolyte, the detection electrode, and the reference electrode based on the heat generated by the heating section;
• and
• a potential difference detecting section that detects a potential difference between the detection electrode and the reference electrode, the potential difference being caused as a mixed-potential between the detection electrode and the reference electrode when an electrochemical reduction reaction of oxygen contained in the gas to be detected and an electrochemical oxidation reaction of ammonia contained in the gas to be detected are balanced in the detection electrode, wherein
• the detection electrode has a distal end, a proximal end, and a central position in the longitudinal direction;
• the detection electrode is partitioned at the central position in the longitudinal direction into a distal end region and a proximal end region, the distal end region being located to be closer to the distal end than the proximal end region is, the proximal end region being located to be closer to the proximal end than the distal end region is;
• and
• the heating section has a heating center arranged to face an offset point,
• the offset point being located to be closer to one of the distal end and the proximal end of the detection electrode than the central position is, the heating center arranged to face the offset point causing a first average temperature in the distal end region of the detection electrode in the longitudinal direction to differ from a second average temperature in the proximal end region of the detection electrode in the longitudinal direction.