GAS SENSOR ELEMENT

The invention relates to a gas sensor element. The purpose of the present invention is to provide a gas sensor element provided with a porous protective layer having improved water repellency when continuously covering water. The invention relates to a gas sensor element. A detection unit is formed by laminating a solid electrolyte body having at least one pair of electrodes on both sides and a heat-generating body including a heat-generating source. A gas sensor element in which a porous protective layer is formed around the detection unit; wherein the porous protective layer is formed from an aggregate containing alumina and a coating material containing silica, and the weight concentration x (wt%) and porosity y (%) of the coating material of the porous protective layer with respect tothe total weight of the aggregate and the coating material satisfy the following formula (1) y < = 0.0058 x2- And 1.266x + 68 (1), the pore volume of the porous protective layer having a pore diameterof 100 nm or less being 0.02 mL/g or less.