Patent ID: 7771576

Claim:
A gas sensor comprising a gas detecting element extending in a longitudinal direction and in which a plurality of ceramic layers are stacked, and wherein a detecting portion is provided at a leading end side of the gas detecting element, the gas detecting element comprising: a first ceramic layer having a first surface and a second surface and having a first through hole penetrating therethrough; a second ceramic layer stacked on a side of the first surface of the first ceramic layer and having a second through hole connected to the first through hole, the second through hole having an opening area larger than that of the first through hole; a bottom ceramic layer which is stacked on a side of the second surface of the first ceramic layer to close one end of the first through hole; a first through-hole conductor provided on an inner peripheral surface of the first through hole; a first connecting layer provided on the first surface of the first ceramic layer and connected to the first through-hole conductor; a second through-hole conductor provided on an inner peripheral surface of the second through hole; and a second connecting layer having one end disposed on the first connecting layer and another end connected to the second through-hole conductor, wherein the one end of the second connecting layer does not reach the first through hole such that the second connecting layer is connected to only a part of the first connecting layer.