Gas sensor element and gas sensor

A gas sensor element configured as a laminate of platelike solid electrolyte bodies, comprising

• electrodes provided on front sides or back sides of the solid electrolyte bodies and leads provided on the front sides or the back sides of the solid electrolyte bodies and connected to the electrodes, respectively, wherein
• the electrodes include a water-permeable third electrode disposed within an internal space of the gas sensor element, the internal space communicating with an ambient atmosphere of the gas sensor element;
• the leads include a water-impermeable third lead connected to the third electrode;
• the gas sensor element has a third insulation layer formed on the front side or the back side of the solid electrolyte body;
• the third lead and a portion of the third electrode are formed on the third insulation layer;
• and
• the third electrode has
• an electrolyte body contact portion which is in contact with the solid electrolyte body through a through hole extending through the third insulation layer in a laminating direction of the solid electrolyte body and
• a third connection portion connected to the third lead on the third insulation layer within the internal space.