Gas sensor

A gas sensor that detects the concentration of a detection target gas in an atmosphere of interest, the gas sensor being disposed on an electrically insulating member and comprising:

• an insulating porous layer formed of an electrically insulating porous material, a reference electrode, a solid electrolyte body, and a detection electrode stacked in this order on the electrically insulating member,
• a reference electrode lead disposed between the electrically insulating member and the insulating porous layer,
• the insulating porous layer defining a through hole in a region sandwiched between the reference electrode lead and the reference electrode, the through hole extending through the insulating porous layer, and
• an electrically conductive member formed of a material having electrical conductivity disposed in the through hole so as to extend from an opening of the through hole at one end thereof to an opening of the through hole at the other end thereof, thereby electrically connecting the reference electrode lead and the reference electrode.