A gas sensor element for detecting a specific gas component contained in a gas to be measured includes: a solid electrolyte layer; a first electrode disposed on the solid electrolyte layer; a second electrode disposed on the solid electrolyte layer; and a porous layer disposed on one of the first electrode and the second electrode such that the gas to be measured is introduced from the outside of said gas sensor element and passes through the porous layer to at least one of the first electrode and the second electrode. The porous layer includes: a first porous layer including a first ceramic porous body which does not include noble metal particles dispersed therein; and a second porous layer provided on the first porous layer and including a second ceramic porous body and noble metal particles dispersed therein.