Sensor element and gas sensor

A sensor element configured to detect a concentration of a specific gas in a measurement-object gas, the sensor element comprising:

• an element body including an oxygen-ion-conductive solid electrolyte layer and having a columnar shape elongate in a longitudinal direction, the element body having a front end and a rear end that are opposite ends in the longitudinal direction and further having a peripheral face that is a surface extending in the longitudinal direction, a part of the element body that is at the front end being allowed to be exposed to the measurement-object gas;
• an inner electrode disposed inside the element body;
• and
• a conducting section including an inner conducting section and an outer conducting section, the inner conducting section being disposed inside the element body and being electrically continuous with the inner electrode, the outer conducting section including a connector electrode disposed at a part of the peripheral face that is near the rear end, the outer conducting section further including a segment disposed on the peripheral face and/or a segment disposed on the peripheral face and exposed to an outside of the sensor element, the outer conducting section being electrically continuous with the inner conducting section,
• wherein a part of the outer conducting section that covers the inner conducting section and/or at least a part of the inner conducting section is a dense segment that has a dense composition with noble metal, alumina, and silica.