GAS SENSOR ELEMENT

In order to suppress a deterioration in the measurement precision while also reducing the manufacturing cost of a gas sensor element, an aspect of the present invention is directed to a gas sensor element including: a stack formed by stacking a plurality of oxygen ion-conductive solid electrolyte layers, and including an internal space configured to receive a measurement target gas from the outside, a first face adjacent to the internal space, and a second face adjacent to an external space; a first pump electrode provided on the first face; a second pump electrode provided on the second face; a first lead formed on the first face so as to extend from the first pump electrode; and a second lead formed on the second face so as to extend from the second pump electrode and configured to be electrically connected to the first lead. At least one of the first and second leads has a shape with a maximum current density of 3.5 A/mm2 or less.