A sensing element for catalytic combustion type gas sensor includes: a heat conducting layer (12); a heater coil (13) buried in the heat conducting layer (12); and a combustion catalyst layer (11) coating or carried by a surface of the heat conducting layer (12) and causing combustion of a detection target gas brought into contact therewith, wherein the combustion catalyst layer (11) and the heat conducting layer (12) are both made of a firing material whose main component is tin oxide. Preferably, the heat conducting layer (12) is made of fine powder of the firing material, the firing material being produced by firing at a higher temperature than a temperature for producing the firing material of the combustion catalyst layer (11). Accordingly, durability and waterproof performance of the gas sensor itself can be enhanced, and without the need to take measures such as special environment setting, mounting thereof on a FCV can be realized.