Gas sensor element

A gas sensor element comprising:

• a detection portion including
• a solid electrolyte layer having a pair of electrodes on opposite sides thereof, the pair of electrodes including an electrode on a measurement target gas side and an electrode on a reference gas side,
• a porous diffusive resistance layer that surrounds the electrode on the measurement target gas side with a measurement target gas space interposed therebetween,
• a shielding layer that defines the measurement target gas space with the porous diffusive resistance layer, and
• a reference gas space protective layer that surrounds the electrode on the reference gas side with the reference gas space interposed therebetween;
• a heat-generating portion stacked on the detection portion, the heat-generating portion having a heat generation source;
• and
• a porous protective layer that surrounds the detection portion and the heat-generating portion, wherein
• the porous protective layer includes a first porous protective layer and a second porous protective layer, the first porous protective layer surrounding at least the porous diffusive resistance layer, and the second porous protective layer surrounding the first porous protective layer and also surrounding the detection portion and the heat-generating portion,
• the first porous protective layer contains none of La, Ca, or Mg, and
• the second porous protective layer contains La, wherein a content of La in the second porous protective layer is in a range of greater than 0 mass % and less than or equal to 1 mass %.